Passenger trains could be running at 200mph across Oxfordshire by 2015 if a proposed high-speed railway becomes a reality.

A new line would use trains similar to the Eurostar service

The new line, modelled on France's TGV network, is being suggested by First Great Western (FGW), whose express trains serve Didcot, Oxford and the Cotswold line on their way to the West of England and South Wales.

The company has launched a six-month study into the idea, in conjunction with the watchdog Rail Passengers Council.

It will look at high-speed services in Europe and Japan, and possible routes for a new line to link London with the Bristol area, as well as timescales for the project and funding.

Based on the cost of building the first section of the Channel Tunnel Rail Link in Kent, which is due to open to Eurostar services next year, a new line could cost £15m per mile, rising to £50m per mile for tunnels. The route, which would have powerful electric trains, could slash journey times.

FGW said it could benefit services to Oxford and beyond. Oxford to London journeys could take about 30 minutes, rather than the current 45 minutes.

A new route could bring London within an hour of Bristol Parkway, rather than 1hr 25min, and Swindon within 35 minutes, instead of 55 minutes.

A dedicated express line would also ease pressure on the existing route from Didcot to London.

Dean Finch, managing director of First Group, which runs FGW, said: "Our research indicates we would need to develop dedicated high speed lines on new routes.

"This would cut costs, avoid disruption to existing services and allow us to develop new integrated, pedestrian-friendly transport interchanges with excellent road access and parking and connecting bus and rail links."

David Robertson, Oxfordshire County Council's executive member for transport, will meet First Great Western representatives in Oxford on Thursday, November 14 to discuss the proposals.

A Strategic Rail Authority spokesman said the company should concentrate on serving its existing customers.

But he added it may consider the future development of routes west from London after 2006, when the franchise for the services FGW runs is due for renewal.

Christopher Irwin, the chairman of both the Rail Passengers Council's strategic issues taskforce and the RPC's Western England committee, said: "The study is going to exhaustively test the business case and route options for a new high speed line."