Ali Akbar Salehi, head of Iran's Atomic Energy Organization, speaks with media in Tehran in October 2004. Iranian President Mahmoud Ahmadinejad named Salehi as interim foreign minister Monday. (Vahid Salemi/Associated Press)

Iranian President Mahmoud Ahmadinejad fired his foreign minister Monday as he was in the middle of an official visit to Africa and named the nuclear chief to serve as the country's acting top diplomat.

In a brief statement on the president's website, Ahmadinejad thanked Manouchehr Mottaki for his more than five years of service but gave no explanation for the change. He named nuclear chief Ali Akbar Salehi, who is also one of the country's several vice-presidents, to serve as interim foreign minister until a permanent replacement is found.

Over the past year, Iranian media have reported that lawmakers were pushing for Mottaki to be dismissed if more UN Security Council sanctions were imposed in response to the country's nuclear program. According to the reports, the lawmakers felt he was not a strong or persuasive enough advocate for Iran on the international stage.

Iran's nuclear policy, however, is determined by Supreme Leader Ayatollah Ali Khamenei. A fourth round of sanctions was imposed in June in response to Iran's refusal to halt uranium enrichment, a key part of its nuclear program that is of international concern because it can be used both for making reactor fuel and atomic weapons.

Iran insists its aims are entirely peaceful, but the UN's International Atomic Energy Agency says its years of investigating have not been able to confirm that.

Mottaki had served as Ahmadinejad's chief diplomat since the president was first elected in 2005.

He was in the middle of a tour of African nations that took him to Senegal, where he delivered a message from Ahmadinejad to the West African nation's foreign minister on Monday.