Former deputy prime minister Wong Kan Seng on Thursday called on Singaporeans not to take economic growth for granted, saying it was needed to create jobs and care for the elderly.

And to avoid a repeat of the past of under-investing in infrastructure, Singapore has to start investing now, said Mr Wong, who was also previously in charge of population matters.

He said the Population White Paper is not about the PAP Government's 6.9 million population projection or the Workers' Party 5.9 million, but about keeping Singapore's economy going at a sustainable rate.

Without growth and coupled with an ageing population, it may come a day for Singapore where the shrinking workforce may not generate enough tax dollars, as it has already happened in Japan and possibly also in Europe.

"Singapore does not have unlimited past reserves to plug the gaps," he said.

As for growing the workforce, Mr Wong noted that Singapore has tried encouraging people to have babies, and for women and seniors to continue working. As both measures take time, it is left with the last option of calibrating the pace of immigration.