The RMT wants maintenance taken away from private companies

LU's managing director Tim O'Toole and Bob Crow of the Rail, Maritime and Transport (RMT) union met near Hammersmith at 0030 GMT on Wednesday.

The area was the scene of a train derailment in October.

The RMT is planning a 48-hour "go-slow" on 9 and 10 December as part of its Tube safety campaign.

Union members voted for the action following two derailments at Camden Town and Hammersmith.

I am making every effort to demonstrate to the unions that I am listening to their safety concerns Tim O'Toole, LU

It has also threatened further industrial action in the week before Christmas if its demands are not met.

The union is campaigning for maintenance work to be taken away from private firms and given back to LU.

Mr O'Toole said: "I am making every effort to demonstrate to the unions that I am listening to their safety concerns.

"A safe Tube is my top priority."

He said taking industrial action would do nothing to improve safety.

But Mr Crow, who welcomed Mr O'Toole comments, said the inspection of the track had shown that lighting and other standards were "unsatisfactory".

He added: "We need to see concrete changes, and next week's safety go-slow is still on."

The two men are due to meet on Thursday for further talks.

On Tuesday, London mayor Ken Livingstone urged unions to work with him to improve conditions on the network.

He said the unions would never be in a better position in terms of the leadership and new management of the system.