Bigger public rental flats in Hong Kong aren't on the cards for at least a few more years, the government said.

In his maiden policy address last year, Chief Executive John Lee set out how the saleable area of all new subsidised flats completed from 2026 onwards will be no less than 26 square metres, and the internal floor area of new public rental units will be at least 21 square metres, apart from those meant for only one or two people.

Housing Secretary Winnie Ho told Legco on Wednesday that the target for flats under the Green Form Subsidised Home Ownership Scheme will be met.

"Despite having the phenomenon of nano flats, the policy address announced last year already called this to a halt," Ho said.

But she added that Hong Kong is not yet ready to build bigger public rental units.

"In the near future, we may not be able to instantly expand the size of [public rental housing] flats, because the sites come with a size constraint. If we build bigger flats, it means we can only build a smaller number of flats," Ho said.

"Once we guarantee an adequate supply of public housing, we will consider increasing the size of public housing flats. It seems that in the second five-year period of the 10-year period, we should be able to achieve that."

Separately, the housing chief said the government is confident that the number of children living in subdivided units will fall, thanks to an increase in the supply of public housing and transitional homes.

She said officials would "keep an open mind" regarding whether families with children can be given priority for light public housing.

In 2021, around 34,000 children aged below 15 were believed to be living in subdivided flats.