The cleric from south London whose name has dominated the mayoral election campaign says he wishes he could sue the Prime Minister.
Suliman Gani was accused in Parliament by David Cameron of being a supporter of Islamic State.
Speaking to ITV News London, Mr Gani strongly denied the allegation but accepted he is unable to launch a libel case because of rules which safeguard MPs' freedom of speech.
On Islamic State, Suliman Gani added:
Watch the interview in full below