Chris Grayling, the transport secretary, said the railway investment would “relieve the burden on taxpayers and fare payers”

A new privately built railway line would be constructed into Heathrow from Waterloo station in London under government plans to expand Britain’s rail network without using taxpayer money upfront.

Chris Grayling, the transport secretary, will announce today that a new private operator will be invited to build the eight-mile link from Britain’s busiest railway station to the mainline near its busiest airport outside the usual scope of Network Rail, the state-funded infrastructure company.

The move will be billed as a significant step by the government, signalling an intention to give big rail upgrades to the private sector in the future. A line between Oxford and Cambridge is already being built using a similar model.

The disclosure will be criticised by Labour, which has advocated more