"If Heathrow passes the air pollution test and is given a green light, that could only mean that the test has been set in such a way that Heathrow was always going to pass it," he added.
"I'm not not trusting anyone, I think Heathrow is off the agenda, I think we have won this campaign.
"The only way that Heathrow can be given the green light now is if the test is rigged."
But Back Heathrow campaign director Rob Gray said Mr Goldsmith's claim was "outrageous".
Mr Goldsmith, a leading Eurosceptic, said he would vote to come out of the European Union if David Cameron failed to deliver "meaningful" reform in Britain's relationship with Brussels.
The Tory MP for Richmond Park insisted he was "not a headbanger" on the issue and wanted to give the Prime Minister a "chance" to deliver reforms.
"If the reforms are not meaningful, if they are not radical, if it doesn't mean that we will have a more decentralised, more democratic union then, of course, I will vote to come out because that would be in the national interest."
