Highgate Village is under attack from the super-rich who are building too many mega-basements and buying up flats for their investment portfolio, a prominent residents’ group has claimed.

The area surrounding Kenwood House in Hampstead has for years been dominated by detached mansions, often with large basements. Many are left empty. But the Highgate Society says it is now seeing more and more bids to build so-called “mega-basements” in the heart of the village, sometimes underneath terraced houses.

In steep Southwood Avenue, off Highgate High Street, there have been three applications for basements submitted to Haringey Council in the last year.

The society’s planning and development chairwoman Elspeth Clements said on Monday: “One does ask, when is it going to stop?

“Highgate will cease to be a village community. At the moment, there is a strong community spirit as there are so many community organisations. Will they be able to continue with this new profile of residents, the super-rich?”

She added: “There is a worry that the new residents won’t participate in the community to the same degree. Then Highgate would be hollowed out. It would become like Mayfair. Highgate is becoming an exclusive enclave of the rich.”

The latest Southwood Avenue proposal is for a cricket pitch-sized basement underneath a three-storey end-of-terrace house.

It has prompted more than 20 objections in less than a month from neighbours, the Highgate Society and the Highgate Conservation Area Advisory Committee (HCAAC). The excavation, to cover the entire footprint of the house, would create an extra three-bedroom flat in the property, which already contains three apartments.

Accountant Stephen Robinson, who lives next door, said: “We are relying on Haringey Council’s planning department to stop and control these developments. These proposals have a major impact on people’s lives and that’s when the council has to step in.” He added: “This is a commercial developer, not a family home, and this is in a conservation area, where people have worked hard to protect it.”

Ms Clements said the application is indicative of a new trend of squeezing too many homes onto cramped sites, to sell off luxury flats to investors.

Charlton Brown Architects, on behalf of owner Lynn Mendoza, declined to comment.

The society spoke out after a study of the village was published last month in the Urban Studies Journal by one of its members, Professor Richard Webber, and Professor Roger Burrows.

The report looked at the community’s monthly battles against the bids of the “fenced-off” super-rich to build mega-mansions.