The prospect of more rail services between the North East and London could be rejected in favour of maintaining links with the rest of the country.
At the moment, six passenger trains an hour can run on the East Coast Mainline (ECM) between Northallerton and Berwick, only two of which are reserved for services to the capital.
The other four carry travellers to and from the Midlands and Manchester, meaning at least one of these would have to be sacrificed to boost routes to the South East.
Philip Meikle, transport strategy director at public transport operator Nexus, said:
Mr Meikle was speaking at a meeting of the North East Joint Transport Committee (JTC).
Plans for the new Azuma trains, built at County Durham's Hitachi plant and which entered service on the ECM last year, included proposals for extra services to London from 2021.
A scheme to improve track capacity was supposed to allow this without affecting other routes, but was 'dropped by Government on cost grounds'.
Gateshead Council leader and JTC chairman Martin Gannon said the ECM had been 'grossly under invested in for years' and branded the lack of track capacity north of York 'unacceptable'.