Birmingham will get a major new railway station to relieve the pressure on New Street - but not for another 40 years at least.

Network Rail confirmed last night that it is determined to build what is being termed the Grand Central option at Eastside, but does not expect the project to get under way until 2046 at the earliest.

Network Rail spokesman Ben Herbert said a fundamental review of rail growth across Birmingham and the West Midlands presently being undertaken would establish the best way of coping with growing passenger demand.

He stressed, however, that speculation about Grand Central should not be allowed to divert attention away from a planned £500 million redevelopment of New Street Station.

Mr Herbert said: "We have enough capacity at New Street until 2046 but we have got to look at longer term demands on the track.

"An argument has developed that it has got to be New Street or Grand Central. As far as we are concerned we have got to do both."

The partnership behind the New Street Gateway project, which promises to revolutionise passenger facilities at the station and redevelop a large city centre site, issued a statement designed to dampen speculation about Grand Central.

Network Rail, Birmingham City Council, Advantage West Midlands and Centro-PTA said there was an absolute commitment to press ahead with the New Street Gateway.

The intervention follows claims by rail experts that a revamped New Street will not have the platform or track capacity to deal with future passenger growth - a claim dismissed by Network Rail.

The statement said: "The plans for Birmingham Gateway are the result of substantial analysis and are part of a long term strategy for the network.

"We believe that this scheme would represent a major investment in Birmingham's public transport network and deliver significant benefits to the city and the wider region.

"It is something that is affordable, can be achieved within a reasonable timeframe, and can be delivered with minimum disruption for passengers.

"The Birmingham Grand Central proposal would be incremental to - and not a replacement for - New Street, and it is most unlikely to be required for a significant period of time.

"Confusion and distraction from the development of the Gateway scheme risks Birmingham's rail transport network going unchanged for the foreseeable future."