Several thousand inmates at a recently shuttered North Korean labor camp may have disappeared, a report by a human rights group alleges.

The Aug. 27 report by Washington-based group Human Rights In North Korea, or HRNK, says that North Korea's Camp 22, a vast gulag located near the Chinese border and reported to be larger than Los Angeles, was thought to have once held between 30,000 to 50,000 prisoners, most of whom were suspected of being disloyal to the regime or were related to people who had shown disloyalty.

The camp may have closed sometime in 2012 after a series of bad harvests (combined with a currency devaluation in 2009) created a food shortage that caused a "large number of prisoners" to perish, the report says, citing a Radio Free Asia article written by a North Korean reporter who defected from the country.

When Camp 22 shut down, an estimated 7,000-8,000 prisoners were transferred from the gulag's compounds, situated in the remote northern county of Hoeryong, to other labor camps. The report says that trains holding inmates were seen departing the area at night, heading south. Many prisoners are thought to have been moved to Camp 25 near Chongjin City or to North Hamgyeong Province's Camp 16, about which virtually nothing is known.

But that still leaves many thousands of prisoners unaccounted for. Their fates are unknown for the time being, as information from inside the so-called Hermit Kingdom often takes years to leak to the outside world, if it gets out at all.

Eerie satellite photographs analyzed by HRNK also suggest the prison closed recently. A "significant number" of Camp 22's guard towers are shown in the photos to have been demolished, along with several of the camp's buildings that were said to have been used for detention and interrogation purposes.

HRNK's report also relied on a small number of interviews with former North Korean prisoners and security officials who escaped the communist nation and with experts and reporters who have informants inside North Korea.

The report was written by human rights researcher David Hawk, a former United Nations official and former executive director of Amnesty International USA.

Hawk used the opportunity of the astounding news to issue a call to action: "If even remotely accurate, this is an atrocity requiring much closer investigation," he wrote.

HRNK Co-chair Roberta Cohen said in a statement, "International arrangements should be negotiated for the entry of the International Committee of the Red Cross into the camps."

North Korea's leaders have never publicly admitted that the prison labor camps exist, even though as many as 200,000 people are thought to languish inside them, subjected to long hours of coerced labor, malnutrition, beatings, rapes and executions.

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  • Female North Korean soldiers march during a mass military parade on Kim Il Sung Square in Pyongyang to mark the 60th anniversary of the Korean War armistice Saturday, July 27, 2013. (AP Photo/David Guttenfelder)

  • Parade participants carry the North Korean national flags, Saturday, July 27, 2013 during a mass military parade celebrating the 60th anniversary of the Korean War armistice in Pyongyang, North Korea. (AP Photo/Wong Maye-E)

  • North Korean women wave to their leader Kim Jong Un during a mass military parade on Kim Il Sung Square in Pyongyang to mark the 60th anniversary of the Korean War armistice Saturday, July 27, 2013. (AP Photo/David Guttenfelder)

  • North Korean veterans of the Korean War wave to their leader Kim Jong Un during a mass military parade on Kim Il Sung Square in Pyongyang to mark the 60th anniversary of the Korean War armistice Saturday, July 27, 2013. (AP Photo/David Guttenfelder)

  • Military tanks parade through the Kim Il Sung Square, Saturday, July 27, 2013 during a mass military parade celebrating the 60th anniversary of the Korean War armistice in Pyongyang, North Korea. (AP Photo/Wong Maye-E)

  • A North Korean missile rolls by as colored smoke trails, left by flying aircraft, streak the sky during a mass military parade on Kim Il Sung Square in Pyongyang to mark the 60th anniversary of the Korean War armistice Saturday, July 27, 2013. (AP Photo/David Guttenfelder)

  • Thousands of North Koreans carry flowers and parade on Kim Il Sung Square, Saturday, July 27, 2013 during the mass military parade celebrating the 60th anniversary of the Korean War armistice in Pyongyang, North Korea.(AP Photo/Wong Maye-E)

  • North Korean dancers parade through the Kim Il Sung Sqaure, Saturday, July 27, 2013 during a mass military parade celebrating the 60th anniversary of the Korean War armistice in Pyongyang, North Korea. (AP Photo/Wong Maye-E)

  • North Korean veterans of the Korean War walk under portraits of the late leaders Kim Il Sung and Kim Jong Il at the end of a mass military parade on Kim Il Sung Square in Pyongyang to mark the 60th anniversary of the Korean War armistice on Saturday, July 27, 2013. (AP Photo/David Guttenfelder)

  • A North Korean soldier salutes while in a military tank as they parade through Kim Il Sung Sqaure, Saturday, July 27, 2013 during the mass military parade celebrating the 60th anniversary of the Korean War armistice in Pyongyang, North Korea.(AP Photo/Wong Maye-E)

  • North Korean soldiers march past the Kim Il Sung Square, Saturday, July 27, 2013 during the mass military parade celebrating the 60th anniversary of the Korean War armistice in Pyongyang, North Korea.(AP Photo/Wong Maye-E)

  • North Korean military soldiers march past the Kim Il Sung Square, Saturday, July 27, 2013 during the mass military parade celebrating the 60th anniversary of the Korean War armistice in Pyongyang, North Korea.(AP Photo/Wong Maye-E)

  • North Korean leader Kim Jong-Un waves to the crowd during a military parade at Kim Il-Sung square marking the 60th anniversary of the Korean war armistice in Pyongyang on July 27, 2013. North Korea mounted its largest ever military parade on July 27 to mark the 60th anniversary of the armistice that ended fighting in the Korean War, displaying its long-range missiles at a ceremony presided over by leader Kim Jong-Un. (Ed Jones/AFP/Getty Images)

  • North Korean soldiers march during a military parade past Kim Il-Sung square marking the 60th anniversary of the Korean war armistice in Pyongyang on July 27, 2013. North Korea mounted its largest ever military parade on July 27 to mark the 60th anniversary of the armistice that ended fighting in the Korean War, displaying its long-range missiles at a ceremony presided over by leader Kim Jong-Un. (Ed Jones/AFP/Getty Images)

  • North Korean soldiers march during a military parade past Kim Il-Sung square marking the 60th anniversary of the Korean war armistice in Pyongyang on July 27, 2013. North Korea mounted its largest ever military parade on July 27 to mark the 60th anniversary of the armistice that ended fighting in the Korean War, displaying its long-range missiles at a ceremony presided over by leader Kim Jong-Un. (Ed Jones/AFP/Getty Images)

  • A North Korean soldier salutes from a tank during a military parade past Kim Il-Sung square marking the 60th anniversary of the Korean war armistice in Pyongyang on July 27, 2013. North Korea mounted its largest ever military parade on July 27 to mark the 60th anniversary of the armistice that ended fighting in the Korean War, displaying its long-range missiles at a ceremony presided over by leader Kim Jong-Un. (Ed Jones/AFP/Getty Images)

  • North Korean soldiers march through Kim Il-Sung square during a military parade marking the 60th anniversary of the Korean war armistice in Pyongyang on July 27, 2013. North Korea mounted its largest ever military parade on July 27 to mark the 60th anniversary of the armistice that ended fighting in the Korean War, displaying its long-range missiles at a ceremony presided over by leader Kim Jong-Un. (Ed Jones/AFP/Getty Images)

  • North Korean soldiers march during a military parade past Kim Il-Sung square marking the 60th anniversary of the Korean war armistice in Pyongyang on July 27, 2013. North Korea mounted its largest ever military parade on July 27 to mark the 60th anniversary of the armistice that ended fighting in the Korean War, displaying its long-range missiles at a ceremony presided over by leader Kim Jong-Un. (Ed Jones/AFP/Getty Images)

  • North Korean soldiers march during a military parade past Kim Il-Sung square marking the 60th anniversary of the Korean war armistice in Pyongyang on July 27, 2013. North Korea mounted its largest ever military parade on July 27 to mark the 60th anniversary of the armistice that ended fighting in the Korean War, displaying its long-range missiles at a ceremony presided over by leader Kim Jong-Un. (Ed Jones/AFP/Getty Images)

  • North Korean soldiers march during a military parade past Kim Il-Sung square marking the 60th anniversary of the Korean war armistice in Pyongyang on July 27, 2013. North Korea mounted its largest ever military parade on July 27 to mark the 60th anniversary of the armistice that ended fighting in the Korean War, displaying its long-range missiles at a ceremony presided over by leader Kim Jong-Un. (Ed Jones/AFP/Getty Images)