Alan Jones The leader of striking Tube drivers called yesterday for fresh talks to try to avert more misery for travellers as he claimed a deal to end the dispute had been "sabotaged".

Bob Crow, general-secretary of the RMT union, contacted conciliation service Acas to ask it to convene a meeting with London Underground (LU) managers.

Mr Crow said there was one outstanding issue, job security, which needed to be resolved before the industrial action could be called off.

The move came as millions of commuters and visitors to the capital suffered travel chaos because of a 48-hour strike that started at 7pm on Tuesday.

Mr Crow said: "The facts are that yesterday the RMT negotiating team and myself attended nearly seven hours of talks at Acas at the end of which I was confident we had the basis of an agreement."

Mr Crow said there was an agreement to consult workers over a revised pay offer, an agreement for Acas to study disciplinary issues, and an agreement on redundancies.

At 6pm, an hour before the strike was due to start, Mr Crow said he signed a document he believed would lead to the action being called off.

He said: "Then, astonishingly, at 6.35pm, whilst awaiting the final typed agreement, we were told by management that they had made a phone call and that they could no longer abide by the agreement."

Minister for London Tessa Jowell said: "The Tube is the backbone of London's transport network so the strike means many Londoners will have had real problems.

"It's vital that both sides resume talks immediately and get the Tube running properly again as soon as possible."