Pakistan is preparing to send 400,000 Afghan refugees back across the border to war-torn Afghanistan, according to a report by Agence France-Presse.

Islamabad claims it should not be responsible for tolerating illegal migrants, while Afghanistan is concerned that its weak economy would suffer from the return of so many refugees.

In addition to the immediate planned deportations, Pakistan may send back almost 3 million refugees within the year, a move that the Washington Post explains could "further destabilize Afghanistan, straining its economy and challenging its fledgling security forces."

Radio Free Europe/Radio Liberty notes that about 1.7 million registered refugees from Afghanistan -- greater than the population of Manhattan, New York -- call Pakistan home.

The UN High Commissioner for Refugees (UNHCR) has called the situation the "largest and most protracted refugee crisis in the world," AFP writes.

Read more from AFP.

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  • Afghan refugees wait for transport to leave for Afghanistan at a repatriation center run by the United Nations High Commissioner for Refugees, on World Refugee Day, in Peshawar, Pakistan, Wednesday, June 20, 2012. (AP Photo/Mohammad Sajjad)

  • Afghan refugees wait for transport to leave for Afghanistan at a repatriation center run by the United Nations High Commissioner for Refugees, on World Refugee Day, in Peshawar, Pakistan, Wednesday, June 20, 2012. (AP Photo/Mohammad Sajjad)

  • Afghan refugee girl Shaziyya Adil, 3, center, sits on a jerrycan, while she and other refugees collect water, on World Refugee Day, in a slum on the outskirts of Islamabad, Pakistan, Wednesday, June 20, 2012. (AP Photo/Muhammed Muheisen)

  • Afghan refugee Ibraheem Rahees, 6, is seen in a slum, on World Refugee Day, on the outskirts of Islamabad, Pakistan, Wednesday, June 20, 2012. (AP Photo/Muhammed Muheisen)

  • Afghan refugee girl Haleema Metawell, 6, looks at other children, not pictured, while standing by her home, on World Refugee Day, in a slum on the outskirts of Islamabad, Pakistan, Wednesday, June 20, 2012. (AP Photo/Muhammed Muheisen)

  • An Afghan refugee youth, center, pours water on himself to cool off, while other refugees are seen collecting water, on World Refugee Day, in a slum on the outskirts of Islamabad, Pakistan, Wednesday, June 20, 2012. (AP Photo/Muhammed Muheisen)

  • Afghan refugee girl Waleemah Syed, 7, holds her brother Marvaiz, 1, by the doorway of their home, on World Refugee Day, in a slum on the outskirts of Islamabad, Pakistan, Wednesday, June 20, 2012. (AP Photo/Muhammed Muheisen)

  • Afghan refugee youth are silhouetted against the sunset as they gather at a slum on World Refugee Day on the outskirts of Islamabad, Pakistan on Wednesday, June 20, 2012. (AP Photo/Anjum Naveed)

  • Afghan refugee youth are silhouetted against the sunset as they gather at a slum on World Refugee Day on the outskirts of Islamabad, Pakistan on Wednesday, June 20, 2012. (AP Photo/Anjum Naveed)