A high-profile Labour peer has publicly stated that voters should not back Ken Livingstone to be mayor of London.

Lord Sugar, the Apprentice boss and millionaire entrepreneur, wrote on Twitter: "I don't care if Ed Miliband is backing Livingstone.

"I seriously suggest NO ONE votes for Livingstone in the Mayoral elections."

In another message to his 1,848,793 followers on the social networking site, the former market trader wrote: "Livingstone must not get in" on May 3.

Lord Sugar, who was made Baron Sugar of Clapton in July 2010, served as a government enterprise "tsar" under Gordon Brown.

Adding further criticism, the Jewish businessman reposted a message from Conservative pundit Guido Fawkes that said: "Ken has claimed that he has no idea how much his wife earns. He is the director of the company that pays her."

However Lord Sugar did not offer himself up as an alternative. "It's been suggested I run for mayor," he wrote. "Not possible, too many commercial conflicts, no time, more to the point I would not know where to start."