A revised train timetable has served up a "massive disappointment", according to a commuter pressure group.

First Great Western revised its timetable in December last year following pressure from commuters about overcrowded trains.

The company said it was replacing Adelante trains, which seat 282 people, with High Speed Trains seating 515, and adding an extra rush-hour service to London.

But on December 10, the first weekday of the new timetable, a rush-hour train was cancelled, forcing passengers to change at Didcot and be late for work.

Zahra Akkerhuys, spokesman for Ox Rail Action, said the new timetable had been beset with delays and cancellations ever since.

She said: "Just when we thought the services could not get any worse, they deteriorate further.

"2007 was such an awful year for commuters and we were expecting the new timetable to improve things. It's been a massive disappoint- ment."

Ms Akkerhuys was speaking after a meeting of Ox Rail Action on Tuesday night, which was organised to allow members to discuss recent fare increases, possible 'strike' action and the new timetable.

Ms Akkerhuys said the group had discussed whether to join Bath-based commuter group More Train Less Strain in action to protest at fare increases of nearly 10 per cent. If the group decided to join the protest, commuters would hand over fake tickets at Oxford Railway Station and refuse to pay fares.

Ms Akkerhuys said: "We have yet to take a final decision, but it was an idea that was warmly received.

"If you are paying £4,000 out of your salary for a season ticket you expect to get to work on time, but First Great Western is not delivering what it is promising.

"Commuters have simply had enough."

Ms Akkerhuys said that the start of the meeting had been held up because several members' trains had been delayed.

Anyone interested in joining the group should email saveourtrains@googlemail.com Richard Rowland, of First Great Western, said the company had received "positive feedback" on the timetable changes, which included six high speed trains from Oxford to Paddington in the morning peak before 8am.

But he added: "We accept that there have been service delivery issues for the timetable, which we are working hard to address."

The threatened commuters' action came as FGW's parent company FirstGroup announced a 10 per cent rise in rail revenues despite "deep-rooted performance issues".

It said it was investing £200m to improve services across the network.