LONDON – A Labour leadership hopeful said on Tuesday he had not meant to upset anyone after claiming he wished he could go back in time and kill former prime minister Margaret Thatcher.

John McDonnell, speaking at a Labour leadership event on Monday, drew loud applause when he said he wished he could "go back to the 1980s and assassinate Thatcher", according to the Telegraph.

McDonnell -- who is unlikely to muster the support of the required 33 Labour MPs by June 9 -- said he meant the remark as a joke.

"In that audience everyone took it as a joke," the left-wing MP for Hayes and Harlington told the BBC. "If people have taken offence I can understand. I'm not the sort of person that would want to upset people."

Political commentator Nile Gardiner -- who once worked alongside Thatcher -- said McDonnell should apologise "for his disgusting, undignified and menacing words".

"Labour should also swiftly and unequivocally disown and condemn McDonnell?s remarks," Gardiner said in his blog for The Telegraph.

The Thatcher comment was made at the GMB union's annual conference in Southport, where five of the six MPs hoping to become the next leader of the Labour Party gathered for their first debate.

So far, only siblings David and Ed Miliband and former education secretary Ed Balls have secured enough backing from other Labour MPs to go through to the next stage of the leadership race.

McDonnell, Andy Burnham and Diane Abbott are also vying for the Labour leadership following the resignation of former prime minister Gordon Brown, but they do not yet have enough nominations to go on to the next level.

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