Property companies are likely to face growing liquidity constraints as banks tighten their new lending criteria due to economic uncertainties.

Meanwhile, the window for companies to raise funds from the equities or bond markets has also closed due to poor market sentiment, according to Pumipat Sinacharoen, a corporate planning executive of SET-listed Asian Property Development (AP).

Mr Pumipat, speaking at a forum organised by the Securities Analysts' Association, said the liquidity constraints could force some developers to delay new projects, sell off existing assets or even seek new partners to stay afloat.

Weak consumer confidence is affecting new sales, while construction costs have jumped sharply with the global increase in energy, steel and commodity prices.

''The problems are only now starting and will carry forward for the next several months. Some developers won't be able to carry the added costs or sell their new projects,'' Mr Pumipat said.

He said the lower segment of the market, with units of around one million baht, was most affected by rising inflation and interest rates.

At the higher end of the market, unit prices were rising as developers passed on construction costs.

Mr Pumipat estimated that in the first two months of the year alone, construction costs rose 4% while architectural and decoration expenses increased 0.4%.

''Actually, I think the main factor in success in property development is not land assets, but rather management's ability to accurately predict market needs. The property sector is a very dynamic one, and the market is changing constantly,'' he said.

Mr Pumipat said developers should aim to maintain a debt-to-equity ratio of one, with firms with higher ratios more likely to face liquidity troubles unless they held high levels of assets in the pipeline for transfer to clients.

Larger companies have an advantage over smaller ones during an economic slowdown or periods of high competition, he added.

''Consolidation is inevitable in the future, and may begin on the project development side,'' Mr Pumipat said.

According to AP, at the end of the first quarter, 37,531 single detached homes remained unsold, or 35% of new supply, while 29,677 condos, or 27%, remained unsold.

Another 27,475 townhouse units, or 25%, were unsold in Bangkok at the end of the first quarter, while unsold duplexes totalled just 8,473 units or 8% of total new supply.

According to Siam City Securities, the prospects for the second half of the property market remain uncertain. The number of unsold units could rise as customers delayed major purchases due to economic uncertainties and rising inflation. Many developers were shifting to lower-priced units in response to weakening support at the medium and high end of the market. According to Siam City Securities, average new unit prices in Bangkok have fallen to 1.85 million baht each, the lowest in 15 months.

New supply in May was continuing to rise at 5.1% year-on-year and 9.2% from the previous month, even as valuations have fallen 21.6% from last year and 19% from the previous month.