“I don’t care if Ed Miliband is backing Livingstone. I seriously suggest NO ONE votes for Livingstone in the Mayoral elections,” he wrote on Twitter.

“Sky doing live Mayoral interview with candidates at 8pm today Johnston v Livingstone is real issue. Livingstone must NOT get in on 3rd May,” he also tweeted to his 1.9 million followers.

The Apprentice star also dismissed suggestions that he should take on the role himself.

He said: “It’s been suggested I run for Mayor. Not possible, too many commercial conflicts, no time, more to the point I would not know where to start.”

Last month Lord Sugar criticised his own party when he attacked Miliband for “jumping on the bandwagon of bank bashing”, which served only to “depress the business environment” in the City.

Speaking during a debate on the Budget, Lord Sugar disputed Miliband’s criticism of moves to award RBS chief executive Stephen Hester a bonus of almost £1m.

“The reality is carry on doing that and these people will go and get a job in a different type of company where the culture of paying bonuses is not frowned upon,” said the millionaire entrepreneur.

“Pay peanuts and you will get monkeys.” He urged: “Change the record, start to install some confidence in the market place.”

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