The population size in 2030 and beyond is for a future government and generation of Singaporeans to decide, Prime Minister Lee Hsien Loong said on Friday during the parliamentary debate on the Population White Paper.

Mr Lee also said that he believes Singapore's population cannot grow indefinitely. So while a population of 6 million will not be sufficient to meet the needs of an ageing population, the total number of people here should be significantly below 6.9 million by 2030, and should not increase further after that.

"Eventually we must reach zero population growth. When and where? Time will tell. It depends not only on our physical limits, but our circumstances and also on the attitudes of future generations of Singaporeans, what they choose," said Mr Lee.

The roadmap till 2020 is clear, because it is possible to have a clearer idea of what the world and Singapore will be like then, he said. And the White Paper projects a slowdown in the inflow of foreign workers and of GDP growth.

Closer to 2020, the Government will review the population projections and policy settings again to decide how much more to slow down beyond 2020.

"We are not deciding on a population of 6.9m by 2030 now. The paper makes it clear. But it has been taken out of context and it took on a life of its own," he said.