Theresa May is facing mounting pressure to condemn Donald Trump's ban on people from seven majority-Muslim countries entering the US, after it emerged that British citizens will be affected.

The ban, which has been condemned as unconstitutional by the American Civil Liberties Union, covers people who were born in or are citizens of Iraq, Syria, Iran, Sudan, Libya, Somalia and Yemen. Those with dual citizenship are also affected, the State Department says.

British citizens who could be hit by the ban include Sir Mo Farah, the Olympic runner, who trains in Oregon but was born in Somalia. Nadhim Zahawi, the Iraqi-born Conservative politician, confirmed that he and his wife are also affected. “I'm a British citizen and so proud to have been welcomed to this country. Sad to hear I'll be banned from the USA based on my country of birth,” the Stratford-on-Avon MP tweeted.

I'm a British citizen & so proud to have been welcomed to this country. Sad to hear ill be banned from the USA based on my country of birth — Nadhim Zahawi (@nadhimzahawi) January 28, 2017

A swathe of Conservative MPs tweeted their condemnation of the the visa ban, with Sarah Wollaston, the chair of the Commons health select committee, saying that Trump should not be invited address the Houses of Parliament at Westminster Hall during his upcoming state visit. “Bang on Sarah, you are speaking for many of us I’m sure,” tweeted Alistair Burt, a former minister under David Cameron.

Heidi Allen, the Conservative MP for South Cambridgeshire, called on Theresa May to condemn the ban, tweeting: “Strong leadership means not being afraid to tell someone powerful when they're wrong. It's an ethos this country is proud of @theresa_may”. Scottish Tory leader Ruth Davidson called the ban "wrong in itself and very worrying for the future".

Just past this midnight, Downing Street, which had refused to condemn the ban, U-Turned, saying they opposed the policy and would "make representations" on behalf of British citizens hit by the ban.