Britain's interior minister said Wednesday that an urgent inquiry is under way after an Islamic Movement leader in Israel was able to travel to the U.K. despite being banned from entering the country.

Home Secretary Theresa May confirmed Wednesday that Sheikh Raed Salah, head of the northern branch of the Islamic Movement in Israel, was detained late on Tuesday by police.

Salah had previously been banned from traveling to the U.K, but was able to evade border checks.

Salah, a militant Palestinian activist, was jailed last year for assaulting a police officer, and previously sentenced over funneling money to Hamas.

May said Wednesday that Salah will be deported.

Earlier on Wednesday, Zahi Nujeidat, spokesperson for the northern branch of the movement, told Haaretz that that there is no explanation for the Islamic leader’s arrest, but he believes that it is largely due to the Zionist lobby and members of the British Jewish community.

The movement’s spokesman claimed that community members pressured government officials not to allow Salah into London for a speaking tour.

“There is no doubt that this is due to the Zionist lobby, and there is no legal or lawful reason for his arrest. We are following the developments in the coming hours, and have sent a lawyer to represent the sheik,” the group’s spokesman said.