Dozens of US citizens working for foreign oil companies in the southern Iraqi oil city of Basra were leaving the country on Friday, the oil ministry said, after a US air strike killed a top Iranian commander in Iraq.

The US embassy in Baghdad urged all its citizens to leave Iraq immediately, hours after the US killed Iranian Quds Force leader Qassem Soleimani and Iraqi militia commander Abu Mahdi al-Muhandis.

Iraqi officials said the evacuation would not affect operations, production or exports.

Company sources said earlier the workers were expected to fly out of the country.

Oil production in Iraq, the second-biggest producer in the Organisation of the Petroleum Exporting Countries, was about 4.62 million barrels per day (bpd), according to a Reuters survey of Opec output.

A spokesman for BP, which operates the giant Rumaila oil field near Basra, declined to comment. Rumaila produced around 1.5 million bpd as recently as April.

Italian energy group Eni said Iraq’s Zubair oil field, which produced around 34,000 bpd net to Eni last year — a fraction of the field’s overall output — was “proceeding regularly”.