Transport campaigners have called on the Government to ensure there is competition between HS2 and the West Coast Main Line despite the routes being run by the same operator.

The Department for Transport announced on Friday that a new franchise - the West Coast Partnership - will cover services on the west coast route from April 2019 and high-speed trains between London and Birmingham from 2026.

The contract will run for the first three to five years of HS2's operation.

James MacColl, of the Campaign for Better Transport, warned that both lines should still compete with each other despite the decision.

He said: " We welcome the integration of HS2 and the west coast services - we've long been arguing that HS2 only makes sense if it is integrated with the rest of the rail and transport network.

"However, this decision must not mean there will be no competition between the lines. The Government must ensure that whoever wins the franchise provides the best service possible for passengers on both routes."

Virgin Trains - a joint venture between Stagecoach and Virgin - has been awarded a new short-term contract of approximately 12 months to continue operating west coast services following the end of the current franchise in 2018.

Patrick McCall, co-chairman of Virgin Trains, said: "There are clearly huge advantages in having continuity of service during HS2's critical enabling works - both up to the start of the new franchise in 2019 and beyond.

"We firmly believe the franchise system has brought unparalleled success to the UK rail industry, with public-private partnerships between Government and franchisees like Virgin Trains delivering success, innovation and growth that would simply never have happened under public ownership."

The £55.7 billion HS2 railway is expected to nearly triple the number of seats during rush-hour from 11,000 to around 30,000.

Phase 1, due to open in December 2026, will see trains travel at high speed between London and Birmingham before running on from Birmingham on the existing west coast line.

A second Y-shaped phase, taking the line to north-east and north-west England and beyond, is due to be completed by around 2032/33.

Transport Minister Andrew Jones said: "By combining the franchise we are ensuring we get the right people on board at an early stage to design and manage the running of both services in the transition stage.

"The new franchise will attract highly experienced companies, who have the right experience, which ultimately means a better deal for passengers - both now and in the future."

The Government said the operator must enhance West Coast services by boosting reliability and punctuality, as well as improving connections to better serve towns and cities along the route, which stretches from London to Manchester, Liverpool, North Wales, Glasgow and Edinburgh.

Rail, Maritime and Transport union general secretary Mick Cash claimed it was a " scandalous decision" which demonstrated why the rail network should be renationalised.

He said: " Tens of billions of taxpayers money will have been spent funding High Speed 2, much of which will now be squandered on corporate welfare on an epic scale.

"Other high speed networks in Europe are publicly owned and Britain's should be the same."