Virgin's Intercity weekend services are affected

The company says Network Rail - responsible for a heavy programme of repairs along the West Coast Main Line - cannot say when work will be completed.

The services affected are those running at the weekend, when most maintenance and repair work is carried out.

They include all Intercity services between London and destinations including Glasgow, Manchester, Liverpool and Birmingham.

Cannot release timetable

The upgrade of Britain's busiest main line has been fraught with difficulties. It was expected to cost �2.5bn, but that figure is likely to reach �8.5bn.

It is impossible for us to be sure that we can alert a passenger if it turns out that the train they intend to travel on is no longer running Virgin Trains spokesman

A Network Rail spokesman admitted: "What we can't do is release the timetable of trains affected by engineering work because the re-timing has not been sorted out."

He explained: "This has been an ongoing situation for months, but so much work is going on over Christmas that we haven't been able to re-schedule all trains."

The spokesman said it would be another few days before Network Rail could tell Virgin how many trains it can run from 4 January.

However, a Virgin spokesman said the industry standard was for Network Rail to tell companies 12 weeks in advance what the timetable was.

Backlog of repairs

He said the company would not take advanced bookings because of its inability to contact passengers if was later discovered the service was not running.

The industry seems unable to tell passengers in adequate time when work needs to be done. Passengers Rail Council

He said: "People don't always buy tickets for themselves, especially when booking online.

"It is therefore impossible for us to be sure that we can alert a passenger if it turns out that the train they intend to travel on is no longer running."

A spokesman for the Association of Train Operating Companies (Atoc) said: "Atoc has been pressing Network Rail for some time to ensure that the 12-week period of advance notice is honoured.

"But to be honest, the amount of work going on at the moment has caused huge problems, although this is not an excuse.

"We have told them it won't do and the companies do need this period of notice if they are to provide anything resembling a decent service."

Busy times

He said it was unlikely that the Rail Regulator would become involved over Network Rail's current failure to keep to the 12-week period of notice, as holiday periods were typically "exceptionally busy times" for maintenance work.

But he said the matter could be referred to the regulator, Tom Winsor, should it recur.

A spokesman for the Passengers Rail Council said: "The industry seems unable to tell passengers in adequate time when work needs to be done.

"My warning to passengers is that they will see more of this short-termism on the railway until Network Rail gets on top of the backlog of repairs."