London mayor Boris Johnson pushed his case for building a hub airport in the Thames estuary while on a visit to Hong Kong.

He reiterated his view that he saw “no circumstances” in which expanding the UK capital’s main airport at Heathrow would be acceptable.

Johnson cited Hong Kong’s Chek Lap Kok airport, built on land reclaimed from the sea on the northern end of Lantau Island 22 miles west of the city centre, as an example of what can be achieved.

Lord Foster, whose practice helped design Chek Lap Kok, has also produced designs for an inner-estuary airport. The mayor has separately proposed an outer-estuary ‘Boris Island’ airport.

Johnson last month admitted he was losing the battle to create an “aerotropolis” in the Thames Estuary.

But Johnson told the Financial Times: “There are absolutely no circumstances in which the expansion of Heathrow will be acceptable to London or of long-term benefit to the country.

“Ambitious cities such as Hong Kong have stolen a march on us and built mega-airports that plug them directly into the global supply chains that we need to be part of.

“For London and the wider UK to remain competitive we also have to build an airport capable of emulating that scale of growth.”

Johnson toured the Hong Kong airport yesterday, where officials told him how the city’s largest single construction project had been planned and designed by British firms

He said that the Chinese were building a “legion of mega-airports” that would be central to economic growth.

“It is hugely impressive yet also devastatingly depressing when you consider that, as long as the vision for aviation in the UK remains steadfastly wedded to Heathrow or a make-do solution, we will not be able to access many of the mega-airports opening here or in the many other dynamic economies building new airfields around the globe,” he said.

“The people of Hong Kong overcame their doubts and delivered a fantastic hub airport at Chek Lap Kok that has since turbocharged their prosperity and economic success.”