Fears have been voiced that the long-promised Thameslink 2000 upgrade may face the axe after a succession of major government transport announcements this week saw no mention of the troubled project.

Thameslink 2000 would double the number of Thameslink trains running from central London to Hendon and Cricklewood, but it is already years overdue.

Mayor of London Ken Livingstone included it in a list of priority transport projects which he published a fortnight ago, in a bid to obtain extra funding from the Government's comprehensive spending review. But there has been no mention of it in any of the past week's transport announcements, which, among other things, endorsed the Crossrail rail link between east and west London.

Lynne Featherstone, Liberal Democrat transport spokesman and chairwoman of the London Assembly transport committee, said: "There has been a deafening silence from the Mayor about the Thameslink 2000 project, which is deeply worrying. The real fear is that it looks like Thameslink is set to be shunted into the sidings of abandoned transport projects."

A spokesman for the Mayor said: "We don't know yet what projects we'll be able to do. Transport for London needs to consider its new funding and increased borrowing powers and see what it can afford. We can't give any cast-iron guarantees on particular projects."

Thameslink will be running a severely reduced service on Monday and Tuesday due to the commissioning of new track and signals in the King's Cross Tunnel.

Services will be reduced by around 50 per cent over the two days.