According to a report from Bloomberg, data from Molior London found more than 6,900 units were started between April and June.
This was the highest rate since the last quarter of 2015.
Purchases of homes under construction were also up substantially (30% to 5,813) over the three-month period, the report noted.
The Molior data added that the stock of unsold homes being built reached its highest (26,573) since it started collecting the data in 2009.
Experts in the new-build sector have called on lenders to raise loan to values available on mortgages to support affordable flat supply.