There are fears the Thames Gateway development will hit wild habitats

A London Wildlife Trust survey found more than 160 hectares were lost in three boroughs over the past 20 years.

The survey showed Barking and Dagenham had lost 96 hectares, Bexley 58 and 6.6 had gone in Harrow.

Losing the grasslands removes the habitat of birds and bats as well as increasing the risk of flooding as they act as sponges, the trust said.

The grassy areas are preferred for development as they are easier to build on than woodland.

If wild grasslands continue to diminish at this rate the quality of life in London will decrease significantly Chief executive of the London Wildlife Trust Carlo Laurenzi

The trust says the wild areas also help to keep temperatures down in London and improve air quality.

Chief executive of the London Wildlife Trust Carlo Laurenzi said the figures showed the grasslands were under threat.

He said: "They are not only host to a wealth of wildlife, they are also used and enjoyed by many Londoners.

"If wild grasslands continue to diminish at this rate, much of London's favourite wildlife like skylarks will disappear and the quality of life in London will decrease significantly.

"The impacts of climate change suggest that London's wild grasslands are much needed now and in the future as they store flood water and reduce heat."

He urged Londoners to join the trust's campaign to stop the loss of the wild grasslands.

There are fears that government plans to develop the Thames Gateway area to create thousands of new homes could result in the loss of green spaces.