DUBAI: The first group of about 400 Iranians expected to be deported from the US under President Donald Trump's immigration crackdown were due to land in Qatar on Tuesday before flying to Tehran, a US and an Iranian official said.

The group included both convicted criminals and people who had entered the country illegally, said the US official, who spoke on condition of anonymity.

The transfer marks an unusual moment of coordination between two nations at loggerheads over Iran's nuclear programme, which Tehran says is purely civilian but Washington asserts is aimed at building a nuclear bomb.

The Iranian official, who also spoke on condition of anonymity, played down the idea of any political deal with the US, which joined Israeli air strikes on Iran and its nuclear facilities in June. The matter was consular, not political, the official said.

The Iranian foreign ministry's director general for parliament affairs, Hossein Noushabadi, said the US was "planning to deport around 400 Iranians, most of whom entered the country illegally, in line with the new anti-immigrant approach of the U.S. government." "In the first step, they decided to deport 120 Iranians who entered the U.S. illegally, most of whom through Mexico," he told the semi-official Tasnim news agency.

The first group of 120 would reach Iran in the next one or two days, he said. A U.S.-chartered flight took off from Louisiana on Monday and was scheduled to arrive in Qatar late on Tuesday so the deportees could be transferred to a Tehran-bound flight, the US official said.