British and US aid workers have been asked to leave Yemen by Houthi authorities in the country, a letter seen by Sky News shows.
In the letter to the country's United Nations coordinator, the Houthi-controlled foreign affairs ministry requests aid workers with US and British citizenship to leave within 30 days.
It follows the second set of joint UK and US airstrikes against Houthi forces, aimed at stopping raids on shipping in the Red Sea.
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The letter also calls on aid agencies not to recruit any workers with dual nationalities from the UK and US in the next 30 days.
The full letter reads: "The Ministry of Foreign Affairs of the Republic of Yemen extends its best regards to the office of the United Nations Resident Coordinator in Sanaa, and through them to all offices of humanitarian organisations working in the Republic of Yemen.
"The ministry would like to emphasise the necessity of informing all officials and workers who hold American and British citizenship of their preparation to leave the country within a maximum period of 30 days from the date of this determination so they will be ready to leave immediately upon the expiration of the period referred to, and the ministry will be sure to inform you via a ministerial letter 24 hours before departure.
"The ministry also calls upon [the humanitarian organisations] not to recruit any employees with dual nationalities from those countries mentioned above during this period.
"The Ministry of Foreign Affairs of the Republic of Yemen takes this opportunity to express appreciation and respect to the office of the United Nations Resident Coordinator."
The UK and US have been carrying out the strikes in retaliation for Houthi attacks on international shipping in the Red Sea.
Defence Secretary Grant Shapps said last night that the second round of strikes was a "success".
In a post on X, Mr Shapps posted: "I want to thank all members of the Armed Forces involved in last night's operations against Houthi targets.
"Their dedication, professionalism and skill made the operation a success, degrading the capabilities that the Houthis use to threaten global trade and the lives of innocent mariners," he said.
Last night's strikes targeted a Houthi underground storage site and locations associated with the Houthis' missile and air surveillance capabilities, a joint statement from the UK, US, Bahrain, Australia, Canada and the Netherlands said.
The Ministry of Defence said four RAF Typhoons, supported by a pair of Voyager tankers, "joined US forces in a deliberate strike against Houthi sites in Yemen".
It added that Paveway IV precision-guided bombs were used to strike "multiple targets at two military sites in the vicinity of Sanaa airfield".
The MoD continued: "These locations were being used to enable the continued intolerable attacks against international shipping in the Red Sea."
It said a "very rigorous analysis" was used to minimise any risk of civilian casualties, which included the decision to attack at night.
The Houthis support Hamas and have been attacking ships they claim are either linked to Israel or heading to Israeli ports. However, several of the group's attacks have been on vessels from other countries.
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