A think tank on Tuesday warned that private home supply could slow in the next six to 10 years unless the authorities can speed up efforts in finding land and implementing development projects.

The Our Hong Kong Foundation forecast that annual private flat completion could fall to 10,400 in the five years from 2027 in the worst-case scenario, which will result in the administration missing its long-term supply target of 12,900 units per year as the amount of government land and railway projects available for construction are expected to drop.

"With existing 'spade-ready' government sites dwindling, it is expected that a supply chasm will occur before the major supply boost from the New Development Areas materialise in the 2030s," the group wrote in a report.

And while private housing supply hit 18,600 for 2021/22, the highest figure since 2017/18, the think tank described it as a "fake rebound".

The foundation explained it was mainly due to a private housing project lowering its average flat size and generating more units.

Researchers also said they're pessimistic towards the government meeting its public housing supply goals. It urged the authorities to assign project managers to each subsidised housing development to help cut through red tape and prevent delays.