How Salah entered UK: alert at wrong terminal

Mr Gould said: "It was important for me to meet the delegation and hear their views on the arrest of Sheikh Salah. As I made very clear to them, this decision was not taken lightly, and was not the result of external pressure.

"The British government opposes extremism in all its forms and retains the right to refuse foreign nationals access to the UK if they represent a threat to our security or society. Sheikh Salah was excluded because he had engaged in unacceptable behaviour."

Mrs May has admitted that "something went wrong" and that she was "urgently reviewing" the situation. She was questioned by the Home Affairs Committee on Tuesday over why Mr Salah was allowed in to the UK and if he was notified of the banning.

She said she had signed the banning order on June 23, two days before Sheikh Salah entered the country. She only confirmed on June 27 that he had entered the country.

According to the Daily Telegraph, he was able to enter Britain without being stopped because border officials believed he was flying to Terminal One rather than Terminal Five and sent an alert to the wrong place.

But Mrs May said there should not be speculation over what had happened and that a full investigation was taking place.

Chairman of the committee, Keith Vaz MP, said: "The committee is less than pleased with what's happened and Parliament is less than pleased."