TEHRAN, Iran -- Iran's outgoing nuclear chief says Tehran has a total of 18,000 centrifuges for uranium enrichment – a process that can be a pathway to making nuclear weapons. The number is higher by a third than publicly known.

Fereidoun Abbasi's announcement came as he handed over his post Saturday to Ali Akbar Salehi, appointed by new President Hasan Rouhani.

Abbasi says 10,000 centrifuges currently operating are of an older model, IR-1, while about 7,000 more of the same model are ready to be installed along with just over 1,000 centrifuges of an advanced new model.

The U.S. and its allies fear Iran is seeking to produce nuclear weapons. Tehran says its nuclear program is peaceful.

Rouhani has pledged to follow a policy of moderation and ease tensions with the outside world.

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  • Iranians celebrate the victory of moderate presidential candidate Hassan Rouhani (portrait) in the presidential elections at Vanak square in northern Tehran on June 15, 2013. Iranian Interior Minister Mohammad Mostafa Najjar said Rouhani won outright with 18.6 million votes, or 50.68 percent. (ATTA KENARE/AFP/Getty Images)

  • Passengers in a public bus flash victory signs in a reaction of supporters of the Iranian presidential candidate Hassan Rouhani, as they attend a celebration gathering, in Tehran, Iran, Saturday, June 15, 2013. (AP Photo/Vahid Salemi)

  • A supporter of Iranian presidential candidate Hassan Rouhani, shown in poster, attends a celebration gathering in Tehran, Iran, Saturday, June 15, 2013. (AP Photo/Vahid Salemi)

  • Supporters of the Iranian presidential candidate Hassan Rouhani, shown in poster at center, attend a celebration gathering in Tehran, Iran, Saturday, June 15, 2013. (AP Photo/Vahid Salemi)

  • A female supporter of Iranian presidential candidate Hassan Rouhani flashes a victory sign as she holds his poster during a celebration gathering in Tehran, Iran, Saturday, June 15, 2013. (AP Photo/Vahid Salemi)

  • Supporter of the Iranian presidential candidate Hassan Rouhani celebrate outside his campaign headquarters in Tehran, Iran, Saturday, June 15, 2013. (AP Photo/Vahid Salemi)

  • A female supporter of Iranian presidential candidate Hassan Rouhani, flashes a victory sign as she holds his poster during a celebration gathering in Tehran, Iran, Saturday, June 15, 2013. (AP Photo/Vahid Salemi)

  • A supporter of Iranian presidential candidate Hassan Rouhani holds his poster as another youth waves to a clergyman outside the campaign headquarters of Rouhani, in Tehran, a day after the election, Iran, Saturday, June 15, 2013. (AP Photo/Vahid Salemi)

  • An Iranian woman flashes the sign for victory as she holds a portrait of moderate presidential candidate Hassan Rouhani during celebrations for his victory in the Islamic Republic's presidential elections in downtown Tehran on June 15, 2013. (BEHROUZ MEHRI/AFP/Getty Images)

  • Iranians supporters of moderate presidential candidate, Hassan Rouhani flash the sign of victory holding a portrait of him as they wait for the final results outside his campaign headquarter in downtown Tehran on June 15, 2013. Rouhani has a clear lead in Iran's presidential election, garnering 51 percent of the vote at 65 percent of polling stations across the country, the interior ministry said. (BEHROUZ MEHRI/AFP/Getty Images)

  • An Iranian woman holds a portrait of moderate presidential candidate Hassan Rouhani as she rides on a motorcycle along Valiasr street in Tehran on June 15, 2013 after he was elected as president. (BEHROUZ MEHRI/AFP/Getty Images)

  • An Iranian woman holds her purple scarf, the campaign color of moderate presidential candidate Hassan Rouhani, as she celebrates along Valiasr street after he was elected as president on June 15, 2013, in the capital Tehran. (BEHROUZ MEHRI/AFP/Getty Images)

  • Iranians gather as they celebrate the victory of moderate presidential candidate Hassan Rouhaniin the presidential elections at Vanak Square, in northern Tehran, on June 15, 2013. Iranian Interior Minister Mohammad Mostafa Najjar said Rouhani won outright with 18.6 million votes, or 50.68 percent. (ATTA KENARE/AFP/Getty Images)

  • Iranian supporters of moderate presidential candidate Hassan Rouhani who won the national elections, celebrate in downtown Tehran on June 15, 2013. (BEHROUZ MEHRI/AFP/Getty Images)

  • Iranians celebrate along Valiasr street, in the capital Tehran, on June 15, 2013, after moderate presidential candidate Hassan Rouhani was elected as president. (BEHROUZ MEHRI/AFP/Getty Images)

  • An Iranian woman celebrates the victory of moderate presidential candidate Hassan Rouhani (portrait) in the presidential elections at Vanak Square, in northern Tehran, on June 15, 2013. (ATTA KENARE/AFP/Getty Images)

  • Iranians celebrate the victory of moderate presidential candidate Hassan Rouhani (portrait) in the Islamic Republic's presidential elections at Vanak Square, in northern Tehran, on June 15, 2013. (ATTA KENARE/AFP/Getty Images)

  • Iranians celebrate the victory of moderate presidential candidate Hassan Rouhani (portrait) in the presidential elections at Vanak Square, in northern Tehran, on June 15, 2013. (ATTA KENARE/AFP/Getty Images)

  • Iranians gather to celebrate the victory of moderate presidential candidate Hassan Rouhani in the presidential elections at Vanak Square, in northern Tehran, on June 15, 2013. (ATTA KENARE/AFP/Getty Images)

  • An Iranian woman celebrates the victory of moderate presidential candidate Hassan Rouhani in the presidential elections at Vanak Square, in northern Tehran, on June 15, 2013. (ATTA KENARE/AFP/Getty Images)

  • Iranians gather as they celebrate the victory of moderate presidential candidate Hassan Rouhani in the presidential elections at Vanak Square, in northern Tehran, on June 15, 2013. (ATTA KENARE/AFP/Getty Images)

  • Iranian women hold a portrait of moderate presidential candidate Hassan Rouhani who won the national election in downtown Tehran on June 15, 2013. (BEHROUZ MEHRI/AFP/Getty Images)

  • A female supporter of Iranian presidential candidate Hasan Rouhani flashes a victory sign, as she holds his poster, during a celebration gathering, in Tehran, Iran, Saturday, June 15, 2013. (AP Photo/Vahid Salemi)

  • Iranians celebrate the victory of moderate presidential candidate Hassan Rowhani (portrait) in the Islamic Republic's presidential elections in downtown Tehran on June 15, 2013. (BEHROUZ MEHRI/AFP/Getty Images)

  • In front of a portrait of the late Iranian revolutionary founder Ayatollah Khomeini, presidential candidate Hasan Rowhani, a former top nuclear negotiator, center, gestures to his supporters at a rally in Tehran, Iran, Saturday, June 1, 2013. (AP Photo/Ebrahim Noroozi, File)

  • An Iranian woman holds a portrait of moderate presidential candidate Hassan Rouhani as she rides on a motorcycle along Valiasr street in Tehran on June 15, 2013 after he was elected as president. (BEHROUZ MEHRI/AFP/Getty Images)

  • Iranians celebrate the victory of moderate presidential candidate Hassan Rouhani in the Islamic Republic's presidential elections at Vanak square in northern Tehran on June 15, 2013. (ATTA KENARE/AFP/Getty Images)

  • Iranians celebrate the victory of moderate presidential candidate Hassan Rowhani (portrait) in the Islamic Republic's presidential elections at Vanak square in northern Tehran on June 15, 2013. (ATTA KENARE/AFP/Getty Images)