You can't trust Ken, warns Boris as he labels fares cut pledge 'a lie'

Warning Londoners "you can't trust Ken," he claimed the Labour candidate "has lied twice in the past about fares" - saying Mr Livingstone broke two earlier promises to cut or freeze fares.

Before flying to Switzerland to speak at the World Economic Forum in Davos, Mr Johnson said: "It's a lie to make this pledge on fares - it's dishonest. It's back to the crazy, bad old days with no grip on spending. I want to draw a line under this now because I don't believe it can happen." He echoed Transport for London's claim that Mr Livingstone's promise to wipe out the Tory Mayor's six per cent fares rise would cost £1.2 billion in revenue.

TfL has repeatedly contradicted Mr Livingstone's claim to be able to fund his fares proposal because of a £729 million surplus in its operating budget, maintaining that money "does not exist", and that any cash raised from fares is spent on investment projects.

A ComRes poll has put Mr Livingstone on a 51 to 49 lead for the May 3 poll, after his vow to cut fares by seven per cent if elected. He hit back at the Mayor today saying: "Boris Johnson is looking rattled and out of touch. Above-inflation fare rises seem to be etched into his DNA, regardless of their impact on Londoners in such tough times.

"A fares cut is eminently affordable and totally necessary, and will save the average Londoner £1,000 over four years." But Mr Johnson said: "He either is lying or he is going to cut bus services in outer London, or cut some big programme of Tube investment or else he'll have to whack up council tax or there will be some new congestion charge.

"Somehow or other he has got to make the books add up. It is not the way forward for London. There is no free lunch here."

Mr Johnson said that when Mr Livingstone was Mayor, in January 2004, fares rose by up to 43 per cent despite him in 2000 pledging to freeze them "in real terms for four years". And in 2003 before the mayoral election, Mr Livingstone said he'd hold future increases to "no more than the rate of inflation".

In his recent autobiography Mr Livingstone admitted breaking the latter pledge because the Government was letting him borrow £2.9 billion for upgrades to the DLR, East London line and North London line, and he had to increase fares "to service the debt".