SINGAPORE - Hold off on popping the champagne for the property sector just yet.

The rate of recent land acquisitions at higher and higher prices by developers is "not sustainable", Redas president Augustine Tan said on Wednesday (Oct 4), the same day a new record was announced for a freehold en-bloc sale.

Given slower economic and population growth, "we do not see a runaway demand in sales transaction volume and property prices in the next few years", he told his audience at the association's annual Mid-Autumn Festival lunch.

Mr Tan noted that buyers remain price-sensitive. "Coupled with the slow growth of the economy and jobs, many, including displaced sellers from en-bloc sales, may downgrade to public housing," he said.

This trend, coupled with rising interest rates, could soften demand for new private homes despite the recent bullish residential land acquisitions, said Mr Tan.

There were 15,000 unsold private homes in the pipeline as at the middle of this year, Mr Tan observed, to say nothing of the more than 7,400 new units to come on the back of 2017's flood of collective sales and the potential for at least 10,000 more to be yielded from this year's government land sales.

"If the prevailing 'bullish' appetite for residential land persists and demand is not sustained, it will hasten the compounding effects of increasing supply and high vacancy, said Mr Tan.

"While the residential property market appears to be on the mend and developers are aggressively replenishing their land bank to sustain their business, the length and amplitude of this new cycle is uncertain," he added.

Meanwhile, commercial, retail and industrial segments "continue to face lacklustre demand", said Mr Tan, pointing to the islandwide vacancy rate of 12.4 per cent for office space and 8.1 per cent for retail space in the second quarter.

The boost in industrial activity has also failed to translate into higher sales and rentals.

These are some of the "many significant associated risks" to the way that developers are replenishing land banks by paying increasingly higher prices, he said.

"The downside risks of geopolitical uncertainty, global economy activity and monetary policy tightening, coupled with domestic structural challenges to the economy and elevated unemployment rate, are ongoing concerns."