Fears were raised last night that a mothballed North railway may never re-open, after Network Rail announced plans to uproot the tracks.

The body, responsible for rail infrastructure in the UK, is proposing to remove the assets from the Leamside Line, which runs from Pelaw in Gateshead to Ferryhill in south Durham.

The line has not been used since 1992, but campaigners believe it could be re-opened as a freight line, and to reinstate local services forced off the East Coast Main Line.

Durham County Council and the North-East Assembly say the proposal will jeopardise any future attempts to restore the line to working order.

However, Network Rail has pledged it will not sell off the land, or dismantle bridges and embankments. It also claimed the track it will remove would not be able to carry trains.

Assembly chairman Alex Watson said last night: "The assembly has written to Network Rail expressing our serious concerns and we will be meeting them to emphasise that the Leamside Line must be protected from any future sell-off. It is critical that this stretch of the Leamside Line is retained for the future. The line is identified in the regional spatial strategy as having possible future uses for freight and passenger services. It must not be lost. The existing rail network is likely to be at full capacity in the foreseeable future and we must not cut back on our options. It would be shortsighted."

Durham County Council director of environment John Richardson said: "We see it as damaging to the long-term potential for the line's reinstatement."

He admitted Network Rail faces financial pressure, but added: "If and when we do come to consider reinstating the line, what they're proposing to do now will significantly add to the costs. That could count heavily against the business case."

The RSS, which governs planning in the North-East for 15 years, has a policy to protect the Leamside line from developments which would prevent its reinstatement.

The absence of any mention of the line in a recent strategy for freight routes suggested there is no immediate plan to revive it. However, a regional planning assessment for the railways did say the line could play a role carrying freight for the nearby Nissan plant at Sunderland.

Network Rail said: "The Leamside line firmly remains part of our property portfolio. We have no plans to sell it on. The track would have to be completely replaced before a service could run over the route. In completing this exercise, Network Rail is making use of the assets which can be salvaged to benefit other parts of network in the North-East."