Lines would run between London St Pancras and Birmingham, Manchester, and Leeds, with Heathrow linked in. The £4.5bn hub would also link London and the north of Britain with destinations on the continent. Schemes like this have been proposed by the Conservatives, and by a report from Arup.
Transport Minister Lord Adonis told The Sunday Times the hub would enable more passengers to travel to Heathrow by train rather than by car.
He said: "I think that it is an attractive idea. It's vital that we have an integrated approach to planning new rail capacity and any new airport capacity that's also required."
A government decision on Heathrow's expansion is due this month.