Islamic Movement in Israel leader Sheikh Raed Salah flew to Britain in June, despite an order from Home Secretary Theresa May banning him over his political activities. He was detained, held for three weeks and released on bail.
The Palestine Solidarity Campaign said Sunday that Salah received a letter from the Upper Immigration Tribunal saying his detention was "entirely unnecessary" and that his appeal has succeeded "on all grounds."
The Home Office confirmed the tribunal's decision.
Salah is an Israeli citizen who has led the fight against Israeli renovation work in Jerusalem's Old City, known to Jews as the Temple Mount and to Muslims as the Noble Sanctuary.