SINGAPORE (Reuters) - Resales of homes in Singapore have soared to almost half of all the private residential property transactions in the city-state, forcing developers to consider cutting prices as a flood of new apartments enters the market.

Falling rentals, currently at their lowest level in four years, and an expected increase in mortgage payments due to rising interest rates are spurring some home owners and investors to put their properties on the market.

On top of this, the stock of completed private homes will grow 7 per cent this year alone, pushing vacancy rates higher, according to official data and property consultants.

"Three or four years ago, everything could just sell by itself, but right now it's very different," property agent Jayson Yap said. "We need to create something more appealing," said Yap, who is advising some of his resale clients to rent furniture and decor to make their properties more appealing to buyers.

Singapore has initiated several rounds of property cooling measures since 2009, including higher stamp duties and tougher mortgage conditions, hitting sales volumes in both the primary and secondary markets.

Resales represented 45.5 per cent of all transactions in the private home market in the fourth quarter of 2014, up from 38.9 per cent three years ago, according to government data. Under a new data collection method, resales rose further to 47.1 per cent in the first quarter of 2015, with developers putting off launches amid weak demand.

Prices of private residential properties fell 1 percent in January to March, the sixth straight quarter of decline, with the high-end market being hit hardest.

Analysts are warning that the low- to mid-range of the market could be the next to feel the pinch.

Smaller companies like Hock Lian Seng Holdings Ltd and Roxy-Pacific Holdings Ltd have the most exposure to the mass-market segment, where a rising inventory of unsold units will put pressure on prices, brokerage Maybank Kim Eng said in a March note.

"Mass market prices have not come down much yet. It has to come down," Maybank analyst Derrick Heng said last week.

Hock Lian Seng's 420-unit joint venture condominium, The Skywoods, had about 189 units unsold as of March, according to Urban Redevelopment Authority data, and discounts are being offered for some flats.

At the end of the first quarter, out of a total 68,201 uncompleted private residential units in the pipeline, more than a third remained unsold.