Despite informal talks being held on Wednesday, London Underground (LU) and the RMT transport union ended Thursday seemingly as far apart as ever from reaching agreement in a dispute over the implications of a new 35-hour week.

Should no last-ditch breakthrough be reached, RMT Tube station staff will strike from noon on New Year's Eve to noon on New Year's Day.

LU had been prepared to meet the RMT at conciliation service Acas to try to resolve the working-week issue and address concerns the union has about new rosters, safety and manning levels on the Tube.

But the RMT saw little point in an Acas meeting after LU had rejected the union's offer to suspend the strike if LU suspended the introduction of new rosters.

London Mayor Ken Livingstone said he "very much regretted" the refusal of the RMT to take part in talks.

He said: "Londoners will be wondering what the RMT actually want. They are getting a 35-hour week with no loss of pay and no reduction in staffing.

"They have a commitment from Transport for London that there will be no overall cut in station staff and they know perfectly well that no new rosters will be introduced which have not been fully validated for safety."

Mr Livingstone said a strike would "do nothing other than spoil a great night out for hundreds of thousands of Londoners".

RMT general secretary Bob Crow said: "It is almost beyond belief that London Underground has turned down flat an offer that would have allowed services to run on New Year's Eve and given us the room for in-depth discussions to take place later. Surely the priority should be to get the services running."