More than 123,000 London homes are at risk of being "delayed or mothballed" due to the lack of clarity around London Mayor Sadiq Khan's second-staircase policy, according to new research.

Along with our parent company Connells, we looked at the number of schemes that are 10 storeys and above which are awaiting determination or pending construction.

Our research found 123,632 homes in 243 buildings were under threat of "significant delays" or cancellations because of the policy that was introduced in February which requires all London buildings taller than 30m (10 storeys) to include a second staircase.

We found that the borough of Tower Hamlets in east London was the most affected by the policy, with 29 schemes in 14,726 homes of 30m or above awaiting determination or pending construction.

The research also highlighted Southwark in south London with 9,189 homes in 24 schemes, Greenwich in south-east London with 28,445 homes in 22 schemes, and Newham in east London with 12,674 homes in 21 schemes as areas most affected by the regulation.

Mary-Jane O'Neill, head of planning consultancy for London & South at LSH and author of the research, said: "If I could say anything to [housing secretary Michael] Gove or the government, it would be really to crack on with getting some more clarity around the regulations because, at the moment, everything is at a standstill."

Lindsay Garratt, planning partner at law firm Winckworth Sherwood, echoed O'Neill, adding: "The new requirement for a second staircase is certainly affecting building viability.

Previously agreed designs and funding models are having to be reconsidered, and this research shows the scale of [the policy's] impact.

It's not just an issue for plans awaiting permission, but recently approved schemes are also going back to the drawing board."