A deal to resolve the future of London Underground remained unattainable on Monday with both sides at loggerheads over who will run maintenance and safety on the tube.

The Greater London Authority poured cold water on media reports that a compromise framework agreement was set to be agreed within days.

Though some progress has been made by the capital's transport commissioner, Bob Kiley there is still little sign of the consensus which would be required to form the basis of a deal. The central unresolved problem is control of maintenance.

"We are progressing in that talks are continuing but we are far from reaching an agreement. The sticking point is how we split maintenance issues. Bob Kiley has to be able to tell contractors 'this has got to be done now' - which he cannot under the current proposals," said a GLA spokesman.

The GLA is also concerned that an audit of the Tube's infrastructure, particularly of the condition of tunnels, by London Underground has still not been carried out. An inspection is being left up to contractors when they take over the system once contracts have been signed.

Potential operators are also believed to have baulked at the concessions which have been made to Ken Livingstone's team including the right to veto the people appointed to run the companies and their pay packages.

Downing Street has refuted media reports that the prime minister has called on John Prescott and Gordon Brown to finalise an agreement with Kiley before the general election is called.

"The prime minister has not stepped into the row. Finding a solution as soon as possible is a priority for all the parties involved. Talks have been continuing and the prime minister is taking an interest in the matter but the deal is in the hands of those taking part in the negotiations," a Downing Street spokesman said.

Adding to the controversy is a Health and Safety Executive report which reveals 273 safety issues which must be resolved before any deal goes ahead. If the executive is not satisfied it can veto final proposals.

A spokesman for the DETR remained "generally optimistic" that a deal was imminent. "Talks are at an advanced stage and we are hoping some sort of an agreement can be reached soon. The 55-point plan drawn up by Bob Kiley will form the basis of a deal," she said.