Senior Tories including Home Secretary Theresa May have attacked Labour's London mayoral hopeful Sadiq Khan, claiming he has links to extremists.

Mrs May, London mayor Boris Johnson and Mr Khan's rival in the City Hall race Zac Goldsmith lined up to criticise the Labour candidate over his past.

Former human rights lawyer Mr Khan has vowed to be "the British Muslim who takes the fight to extremists" if he wins the May 5 election.

But Mr Johnson told activists at the Conservative spring forum: "Sadiq Khan has shared platforms - to put it at its mildest - with some pretty dodgy people with some pretty repellent views."

Mrs May, who said she had excluded "more hate preachers than any other home secretary", said: "I worry when I see Sadiq Khan in contortions over whether Babar Ahmad - a man subsequently convicted of conspiracy and providing material to support terrorism - was a friend of his or not; when I see that he has shared a platform with a group backed by an extremist imam; when I see that he defended someone threatening 'fire throughout the world' as simply using 'flowery' language.

"This is not the judgment London needs in a mayor at a time when we face a significant threat from terrorism."

Mr Goldsmith told the event: "London cannot afford a Labour mayor who opposed stop and search, whose party leader thinks shooting terrorists is a bad idea, a mayor whose career before becoming an MP involved coaching people in suing our police.

"On this issue above all others there can be no ambiguity - no looking both ways."