Unions have called off the threat of further stoppages after Ken Livingstone promised to take the pay dispute to non-binding mediation when he takes over the running of London Underground.

Although Transport for London is not likely to take over until next April, union leaders said they felt they would get a big pay rise for Tube workers.

But London Underground say the mayor is simply delaying the problem, not solving it.

We hope we can now look forward to a future of good industrial relations in the interest of our members and all Londoners

Mick Rix, Aslef leader

Drivers' union Aslef and the Rail, Maritime and Transport (RMT) union decided to call off the long-running dispute after meeting with the mayor for an hour on Wednesday.

Two 24-hour strikes by both unions over an imposed pay rise of 3% have paralysed the London Underground network during the past few weeks.

Union leaders and the mayor have agreed to sit down with mediator Professor Frank Burchill of Keele University.

RMT general secretary Bob Crow said: "The mayor has given a guarantee that as soon as he takes control of London Underground, the just pay claim will be referred to independent non-binding mediation and that the outcome will be backdated to April of this year."

He added that he was confident the unions could secure a higher pay rise for his members once they put their case forward.

Speaking to BBC London, Mr Livingstone said he would be "surprised" if the unions got the full 5.7% for which they were asking.

But he said he hoped, together with London transport commissioner Bob Kiley, to negotiate a deal that would limit further disruption.

The issue remains unresolved. It has simply been batted into next year

Bob Mason, London Underground

He said: "When Bob Kiley takes over in the spring I want him to sit down and negotiate a four-year deal so that what we get is industrial peace.

"Then Londoners can look forward to the fact that they don't have to worry about how they will get to work."

Both unions attacked the government and London Underground managers who had refused to go to mediation over the dispute.

London Underground had pointed out it had already attended three rounds of talks at the conciliation service Acas.

Mick Rix, general secretary of Aslef, said he welcomed the intervention of the mayor.

He said: "We hope we can now look forward to a future of good industrial relations in the interest of our members and all Londoners."

Bob Mason, human resources director for London Underground, was pleased the unions had called off further strikes.

He added: "But the issue remains unresolved. It has simply been batted into next year when the mayor will face the same dilemma the management face today.

"Making the most of the limited money available to us, we have to pay our staff a fair wage and improve the Tube for our customers."