British commentator Sami Hamdi has been detained by US immigration, who have revoked his visa and banned him from completing his speaking tour, a Homeland Security official said.
Immigration and Customs Enforcement (ICE) has Mr Hamdi in custody, DHS spokesperson Tricia McLaughlin posted on X.
"Under President Trump, those who support terrorism and undermine American national security will not be allowed to work or visit this country," she wrote.
"This individual's visa was revoked and he is in ICE custody pending removal."
Mr Hamdi spoke at a gala for the Council on American Islamic Relations (CAIR) in Sacramento, California on Saturday and was scheduled to speak on Sunday at one of the group's events in Florida, the organisation said in a statement.
CAIR said he was detained at San Francisco International Airport.
Conservative figures had been urging the Trump administration to expel Hamdi from the US.
Mr Hamdi, who is managing director of the International Interest, a global risk and intelligence company, has appeared as an analyst and commentator on British TV networks including Sky News.
CAIR called for his release and accused the Trump administration of detaining him over his criticism of the Israeli government.
CAIR's deputy director, Edward Ahmed Mitchell, said Hamdi had previously denied supporting Islamic militants.
"Abducting a prominent British Muslim journalist and political commentator on a speaking tour in the United States because he dared to criticise the Israeli government's genocide is a blatant affront to free speech," CAIR said in a statement.
A Foreign Office spokesperson said: "We are in contact with the family of a British man detained in the USA and are in touch with the local authorities."
Since January, the Trump administration has pursued a sweeping crackdown on immigration, including increasing social media vetting, revoking visas for people it claims praised the murder of conservative activist Charlie Kirk, and deporting student visa and green card holders who have voiced support for Palestinians and criticised Israel's conduct in the Gaza war.
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