Sadiq Khan has voiced is opposition to expansion at Heathrow, throwing his weight behind an additional runway being built at Gatwick.

The Tooting MP, who hopes to become Mayor of London, announced his stance on airport expansion a week after Zac Goldsmith, MP for Richmond Park and north Kingston, said he would enter the mayoral election race.

Conservative Mr Goldsmith, who will bid to become a candidate if his constituents give him the nod, has been outspoken about his opposition to expansion at the west London airport and has defied his party.

Mr Khan, who has previously remained silent on his stance on airport expansion, said he understood there needed to be additional airport capacity in the south-east, but believed expanding Heathrow could create illegal levels of air quality and create excessive noise pollution.

He said: "As Mayor my decisions will be guided by the question 'what do Londoners need'. In my view Londoners need a better Heathrow, but not a bigger Heathrow.

"If we are to create more jobs and opportunities for Londoners then we simply must have more airport capacity in the south-east.

"But this cannot come at the expense of our environment, or wreck the lives of thousands of Londoners in the process."

The Labour MP, who was re-elected for his third time in Government last month, said expanding Gatwick would be the "best option for Londoners".

He added: "I think that Heathrow needs to be better, not bigger. Competition with Gatwick will help achieve that.

"I will fight to protect the workers at Heathrow and look into the feasibility of creating a 'Heathwick' high speed rail link."

Mr Khan’s rail link plans would see the two airports connected by high speed rail and allow fast transfers.