A former environment minister has told prime minister David Cameron he must decide whether he is “man or mouse” and drop his objection to building a third runway at Heathrow airport.

Tim Yeo, a former environment minister and head of the Parliamentary climate change committee, said the “environmental objections” to the expansion of Heathrow were “disappearing”.

Yeo previously opposed the third runway, but said the “facts had changed” on the issue.

Writing in the Daily Telegraph, Yeo said Cameron must “find his sense of mission” and push ahead with the controversial project. “The Prime Minister must ask himself whether he is man or mouse,” he writes. “Does he want to be another Harold Macmillan, presiding over a dignified slide towards insignificance?

He is one of a number of ministers who have voiced their support for a third runway. Housing minister Grant Shapps told the Daily Telegraph: “As a great trading nation we need to have sufficient numbers of ports to get people and goods in and out.

“I back the Chancellor’s position to the hilt when he said in the budget we clearly need to review the airport capacity in the South East.

“All the options need to be considered while being mindful of our election manifesto.”

Northern Ireland secretary Owen Paterson is said to have raised the issue at Cabinet last month saying that blocking expansion risked choking off economic recovery.

Former Labour Chancellor Alistair Darling also said over the weekend that the Heathrow capacity issue could not be ignored.

“Everybody who flies wants a runway, and nobody who lives near one wants one at all. There is a consensus we actually do need more capacity,” he said.

Another Conservative minister told the newspaper that the current policy on Heathrow is “bonkers” and that both the estuary airport and the third runway may need to be considered.

The minister said: “You might need to do Heathrow as a medium term stop gap and an estuary airport as a long-term thing.

“London is a global supercity, as demonstrated by the Olympics, and there will come a time when we need a ten-runway estuary airport acting 24 hours a day, seven days a week.”

A growing number of ministers led by George Osborne, the Chancellor, are understood to believe that the prospect of another runway should be included in a forthcoming consultation on airport capacity.