By political editor Paul Francis

Boris Johnson has triggered further confusion over his scheme to build an airport in north Kent after declaring on television that he had no plans to build one.

The Mayor of London was challenged over his plans during last night’s Question Time on BBC1.

Host David Dimbelby quizzed him about the project, saying it was an example of how he was at odds with party leader David Cameron.

In reply, Mr Johnson said: "I don't want to build an airport in the Thames Estuary."

The comment was seized on by his opponents as a sign that the mayor was distancing himself from the scheme, which has been estimated to cost £40billion.

But his office has now issued a statement saying he was referring to there being "no actual plans in place".

"The Mayor was referring to the fact that there are no actual plans in place to build an airport," said a spokesperson.

"However he believes the complex and critical decisions on Britain’s aviation future require mature exploration of every possible option.

"He has set up a steering group whose role is to oversee further study and research on issues in the estuary such as energy, flood management, transport, ecology and regeneration. Their research will be invaluable when deciding if a new airport there could meet London’s future needs."

Labour's transport spokesperson and vice-chair of the London Assembly's transport committee, Val Shawcross, said: "There is real confusion about the mayor's aviation plans and a multi-million pound, six-runway airport is not something to flip-flop over."