Senior Conservative politicians will refuse to support their party's policy on expansion at Heathrow at the next general election, it has been claimed.

Foreign Secretary Philip Hammond and Mayor of London Boris Johnson are among those expected to rebel against their party line, having told constituents they will strongly oppose the building of a third runway.

Mr Johnson, who was selected as the Conservative parliamentary candidate for Uxbridge and West Ruislip, has already spoken out against expansion but was dealt a major blow when the Airports Commission dismissed plans for Boris Island airport in the Thames Estuary.

The commission announced in September it would not add Mr Johnson's plans to its shortlist of options to increase air capacity 2030, leaving only a new runway or expanding at Heathrow or an additional runway at Gatwick.

The Conservative party initially ruled out expanding at the west London airport, but a rethink from Chancellor George Osborne caused the party to change their view.

A number of other Conservatives, including Richmond Park MP Zac Goldsmith, Home Secretary Theresa May and International Development Secretary Justine Greening have also spoken out against the expansion.

The breakaway from the party line could potentially open a rift at the top of the Conservative party, the Observer claimed.

Mr Goldsmith said: "A decision to proceed with Heathrow expansion would split the cabinet and wider party, and would trigger an unprecedented backlash among residents and campaign groups.

"If Tony Blair, with a massive majority and no real political interest in this part of London, couldn’t pull it off, there is very little chance anyone else will be able to. Heathrow expansion simply is not deliverable."

Foreign Secretary and MP for Runnymede and Weybridge Philip Hammond said: “I remain of the view that London’s role as an international hub can be protected by the provision of an additional runway at Gatwick and enhanced public transport infrastructure between Gatwick and central London and between Heathrow and Gatwick. 

“I look forward to the publication of Sir Howard Davies’ Airports Commission’s final report next summer.” 

Business Secretary Vince Cable, MP for Twickenham, has also spoken out against the expansion of Heathrow.

Howard Davies, chairman of the Airports Commission, is expected to deliver his final report on airport expansion in summer 2015.