The Conservatives have pledged to build a £15.6bn high-speed rail line from London to Leeds instead of a third runway at Heathrow airport.

The party said if it were elected it would launch a competition to build the 200-mile line in its first months in office, and that it expected construction to begin in 2015 and complete in 2027.

It would pay for it by bringing forward 25% of the government’s annual expenditure on rail (equivalent to £1.3bn today and £15.6bn over 12 years).

Theresa Villiers, shadow transport minister, said the plans could add £60bn to the UK’s economy and cut internal flights by 66,500 a year.

She also said her party did not support plans for a third runway at Heathrow airport.

David Frost, director general of the British Chambers of Commerce, said: “I have to question the rationale for not expanding Heathrow and, while high-speed rail is good, it will cost a substantial amount of money and this must not be taken from our road budget.”