Young people postponing marriage and delaying having children because they cannot afford a flat would get subsidies under a proposal floated by a government housing adviser.

Michael Choi Ngai-min says the problem of an ageing population could worsen if people in their 20s and 30s defer their family plans for too long.

The Long Term Housing Strategy Steering Committee, of which Choi is a member, will consider the idea and others tomorrow.

It was understood that the advisers will also look at redeveloping old public estates, to shorten the public housing waiting list of 210,000.

"I do agree that the younger generation shouldn't be given the highest priority, as many should be able to improve their lives on their own," Choi said yesterday.

"But to look at the issue from the ageing population point of view, there is a group of young people in their late 20s and early 30s deferring their plans to start families because they cannot get a flat. The ageing problem is going to be worse if they postpone their marriages and plans to have babies."

Government statistics show that the proportion of never-married men and women in the prime marriageable age of 20 to 49 increased from 39.3 per cent and 34 per cent, respectively, in 2001 to 46.8 per cent and 38.9 per cent in 2011.

Choi hopes the government will extend the coverage of existing schemes to the age group and consider offering them loans. He conceded that it would be difficult to define the exact age bracket that should be eligible.

Some advisers wanted more help for single people, a group that has a annual quota of 2,000 public housing flats.

Chief Executive Leung Chun-ying is expected to announce plans to build a land reserve for housing in his policy address on Wednesday.

It is thought he will reveal the reclamation sites shortlisted by planning officials.

Two examples are Lung Kwu Tan, in Tuen Mun, and Siu Ho Wan, in North Lantau. Together, they cover an area of more than 500 hectares.