The company said it was making the "best use" of its resources

Martin Salter, Rob Wilson and Ed Vaizey have described some First Great Western (FGW) services to London as unreliable and overcrowded.

They called on FGW and the Department for Transport to take "urgent action".

The company said on some lines extra trains and seats had been added but a small-scale review was under way.

We are aware of the local issues and are monitoring the situation closely Richard Rowland, FGW

Mr Salter, MP for Reading West, said: "First Great Western have made an already mediocre service even worse with their ill thought out and half-baked timetable changes."

Conservative MPs Rob Wilson, Reading East, and Ed Vaizey, Wantage, also condemned "the chaos caused by the new timetable".

"We are asking the Department for Transport to take urgent steps to introduce greater capacity to relieve overcrowded commuter trains," said Mr Wilson.

But Richard Rowland, FGW's regional manager, defended the changes.

He said: "The new timetable represents the best use of our resources to benefit the maximum number of people.

"We are aware of the local issues and are monitoring the situation closely."