The Mayor of London is sending mixed signals over London City Airport , according to London Assembly Green Party member Caroline Russell.

She compares Sadiq Khan’s support for the £344million expansion of the Docklands hub earlier this year with his latest statement which appears to cast doubt on the wisdom of his decision.

In May, he withdrew City Hall’s objection to the airport buying land from the Greater London Authority that it needed to expand, put in place by former Mayor Boris Johson.

Mr Khan conceded that the Government approved the plan “without the additional protections that my predecessor and I both sought”.

Mr Johnson, a keen advocate of a Thames Estuary Airport, had blocked the plan that would allow more flights from the Docklands, basing his objection on noise nuisance and air quality.

Read more Where's the link, says judge sentencing airport protesters

The scheme involves expanding the terminal and building a new lane for aircraft to taxi, which would allow it to increase the number of flights by 40% and accommodate bigger planes.

Mr Johnson had called in and rejected the proposal but it was cleared by the planning inspector in July.

The Government trumpeted the successful conclusion of the inquiry as part of its post-Brexit “open for business” message – with Chancellor Phillip Hammond jumping in to make the announcement ahead of business and local government ministers.

A passenger plane comes into land at London City Airport

Mr Khan said this week: ”Now that expansion has been approved we need to ensure air quality will not be adversely affected.

“I am glad measures will be put in place by the airport, should it expand – such as the provision of electric power to reduce aircraft engine use on the ground and improvements in the ground vehicles.

“There will also be extensive monitoring undertaken and if the airport does not deliver on its commitments not to worsen air pollution I will hold them to account.”

But Ms Russell highlighted the discrepancy. She said: “While it’s welcome news that the Mayor recognises that further airport expansion will make it impossible to end the illegal levels of air pollution across London, many people will be confused about why he removed City Hall’s objection to the City Airport expansion back in May.

Read more Reaction to news of London City Airport's clearance to expand

“The Mayor should stand up for the people of east London, stop sending mixed messages and say he’s against the expansion of City Airport if it means that his air pollution plans will be in tatters.”

London City Airport has said that it is committed to managing and reducing emissions from ground and air operations commitment. The larger aircraft that LCY will be able to accommodate will be more energy efficient and quieter, it says.