Adverts which suggested gay people could be cured have been banned from London buses, transport chiefs said.

The campaign was due to run for two weeks on the side of vehicles serving five routes in the capital, including top tourist destinations such as St Paul’s Cathedral, Oxford Street, Trafalgar Square and Piccadilly Circus.

The posters, by Christian group Core Issues Trust, stated: “Not gay! Post-gay, ex-gay and proud. Get over it!” and were believed to mock pro-gay group Stonewall’s recent campaign which featured adverts saying: “Some people are gay. Get over it.”

But following a huge public outcry which labelled the Core Issues’ campaign homophobic, London mayor Boris Johnson, who chairs Transport for London (TfL), ordered the adverts to be pulled.

Mr Johnson, who is standing for re-election next month, said: “London is one of the most tolerant cities in the world and intolerant of intolerance.

“It is clearly offensive to suggest being gay is an illness someone recovers from and I am not prepared to have that suggestion driven around London on our buses.”

The doomed campaign, which was backed by Christian group Anglican Mainstream and cleared by industry regulator the Advertising Standards Authority, claimed therapy could change sexual orientation. It was due to run on London buses from Monday.

Core Issues’ co-director Mike Davidson criticised the decision to axe the adverts, saying: “I didn’t realise censorship was in place.

“We went through the correct channels and we were encouraged by the bus company to go through their procedures. They approved it and now it has been pulled. I would be interested to know on what basis they have done that.”

Stonewall spokesman Andy Wasley welcomed the move, saying: “We are delighted by TfL’s clear commitment to diversity. It is fantastic that no adverts will be promoting voodoo, gay-cure therapy in London.”