Livingstone pledges to improve public transport if re-elected

The prime minister walked past people waving placards bearing quotes of his earlier criticisms of Mr Livingstone, who ran as an independent in 2000.

But he said on Thursday the mayor's record justified his re-election.

Tory candidate Steve Norris also launched his manifesto on Thursday, while Liberal Democrat candidate Simon Hughes MP unveiled his bid last Monday.

Mr Livingstone was suspended from the Labour Party in 2000 for running as an independent after failing to be selected as the party's official mayoral candidate.

'Proud' of record

At the time Mr Blair said he was a potential "disaster for London".

But as the mayor launched his campaign at the Tricycle Theatre, in Kilburn High Road, Mr Blair said he was "proud" of Mr Livingstone's record as mayor.

"People ask me why did I change my mind, the reason is I was able to judge on a record that he had and I have talked to Londoners," the prime minister said.

Mr Livingstone was re-admitted to the Labour Party in January.

It was a myth that the number of police officers had nothing to do with crime Ken Livingstone

Unveiling his manifesto, the mayor said he wanted to provide affordable childcare for every child in London.

He also pledged to increase the number of uniformed police officers and continue to fund more beat police.

"It was a myth that the number of police officers had nothing to do with crime or the fear of crime," he said.

"London is breaking new ground, with a return to dedicated beat policing and more police officers to protect our communities and reclaim our public spaces."

He also committed himself to more providing more buses and making them more accessible and environmentally friendly.

"This is a programme for the whole of our city, inner and outer," he said.

"It is a vision of a safer London with tough policies to deal with crime, but reflecting the wider needs of Londoners for clean air, decent public transport and affordable childcare."