Mayor confirms he will mount a legal challenge if Brown greenlights a third runway this week

Boris Johnson has confirmed that he will launch a legal challenge against the government if it gives the go-ahead to a third runway at Heathrow.

The London mayor has joined scores of protesters calling for prime minister Gordon Brown to reject the plans, ahead of an expected announcement on Thursday.

Boris Johnson
Johnson: "Any challenge will be supported by, I think, the overwhelming majority of people across London"

Speaking on BBC Radio 4’s lunchtime programme The World at One, Johnson said the proposed expansion was “doomed and impractical” and called for alternative solutions.

He said: “I think they should recognise that, even if they go ahead, this project will take so long, and be so bedevilled by objections, that we'd be just as well off looking at alternatives, and that's why what we have been doing is looking at all the possible alternative solutions.”

He said he thought the majority of Londoners would support his commitment to challenge an approval for the scheme in court.

“There will be any number of bases on which it will be possible to challenge this decision, and any challenge will be supported by, I think, the overwhelming majority of people, not just in west London but across London, by people who do not want to see their quality of life eroded by aircraft noise, particularly when it's unnecessary and we can come up with an alternative solution.”

More than 100 MPs have signed an early day motion opposing the expansion plans. But business leaders and airline bosses today increased pressure on the government to approve the scheme.

Newspaper adverts backing the plans were published by the Future Heathrow coalition, and industry figures have said approval is vital for the British economy.