Opposition veteran and former Potong Pasir MP Chiam See Tong has weighed in on the population White Paper in an online video put up on Wednesday.
Like many other critics, he said he was "appalled" at the projections that Singapore's population could hit 6.9 million by 2030.
The Singapore People's Party chief said the "huge figure" surpasses the population of Scandinavian countries and will put tremendous pressure on Singapore's infrastructure - especially housing - in the future.
"That is the day when Singaporeans will suffer the pressure of high population, truly high population in Singapore," said Mr Chiam of the 2030 projection.
He criticised the Government for pursuing a "growth at all costs" policy since Singapore's independence and bringing in foreign workers who took away jobs from Singaporeans.
"You may ask what is the solution. I think the best solution is to open the doors for more Singaporeans to give more of their ideas. Singapore is purportedly a democratic country. For that purpose, we have to invite more Singaporeans to join the opposition so they can give more ideas to the government," said Mr Chiam.
"I'm sure when you open the flood gates, many many more Singaporeans will come forward with brilliant ideas and the problems can be solved easily," he said.