The security services repeatedly prevented Scotland Yard from pursuing criminal investigations against hate preacher Anjem Choudary, it has been claimed.

Met counter-terror officers often felt they enough evidence to build a case against the radicalising cleric, only to be told to hang fire by MI5, because he was crucial to one of their on-going investigations, a source has claimed.

The situation led to tension between the two sides with police feeling “frustrated” that Choudary was not being brought to justice, the source added.

After almost 20-years at the forefront of radical Islam in Britain, Choudary was finally convicted of a terrorism offence last month and faces up to ten years in prison when he is sentenced on September 6.

But following his conviction it was revealed that the 49-year-old former lawyer had been linked to at least 15 terror plots dating back as far as 2001.