Iran's official Islamic Republic News Agency reports that Mottaki was in Senegal to deliver a message Monday to his counterpart on behalf of Iranian President Mahmoud Ahmadinejad. Later reports indicate that Ahmadinejad appointed Salehi as interim foreign minister.
"In a letter to Manouchehr Mottaki, President Ahmadinejad appreciated his services and prayed for his success," the report from IRNA read.
Sadegh Zibakalam, a political science professor in Tehran, told al-Jazeera that Mottaki and Ahmadinejad had their differences.
"When he was appointed five years ago, there were a lot of rumors that Mottaki had been imposed on Ahmadinejad and he wasn't pleased to have him," he said. "Since then, on half a dozen occasions, there had been rumors that Ahmadinejad had either sacked Mottaki or asked him to resign."
The firing follows talks between Iran and Western allies in Geneva over Iran's controversial nuclear program. Iran said last week it was producing yellow cake uranium for enrichment. The West believes Iran is operating a covert nuclear weapons program, something Tehran denies.