The Mayor of London will join a legal challenge to the government’s plans to add a third runway in Heathrow.

Leaders of Richmond, Wandsworth, Hillingdon and Windsor & Maidenhead councils are fighting the airport expansion.

The cross-party campaign has already signalled they will explore the possibility for a judicial review if the plans are approved.

The challenge will centre on the environmental damage and harm to the public the runway would cause.

The four councils have argued that Heathrow is the wrong place for airport expansion in the south-east. They argue that existing noise levels and already poor air quality standards render a third runway “undeliverable and inconceivable”.

Richmond leader Cllr Gareth Roberts said: “We have always said the evidence doesn’t lie. Heathrow already churns out unlawful levels of air pollution, offers woefully inadequate public transport connectivity and has Europe’s worst noise footprint - and that’s with just two runways. The expansion will make all these issues worse."

Wandsworth leader Ravi Govindia said: “We welcome the Mayor’s support for our campaign. Londoners should not be asked to suffer the extra noise and pollution from the additional flights and vehicle movements that a third runway would bring.

“Heathrow is already the busiest airport in Europe and brings in more flights over built-up areas than any other European airport.”

Cllr Simon Dudley of Windsor and Maidenhead said: “While we await a Commons vote on the third runway we hope the concerns we have aired over and again about the impact these proposals would have on the health and quality of life of our residents do not go unheard.”

Hillingdon leader Cllr Ray said: "Throughout the whole consultation process, the Government has failed to address the concerns not only of the impacted communities but also the advice from the Transport Select Committee.”