A huge influx of foreigners who now make up one in four people in Singapore boosted the population, according to new statistics which highlight the city-state's concerns over falling fertility rates and a greying population.

One in three Singaporeans in their early 30s is single, up from one in four 10 years ago.

"We expected the prevalence of singles to be the same or slightly higher, but we didn't expect this magnitude," chief statistician Paul Cheung told reporters.

The over-65 bracket increased from six percent of the population to 7.3 percent in the past decade, and the median age rose from 29 to 34.

In recent months the Singapore government has unveiled a raft of measures to generate a baby boom as the birth rate fell below 1.5 children per woman, well down on the 2.1 figure deemed necessary to replace the population.

Sweeteners have ranged from monetary incentives to have more than one child to flexible work hours so couples can spend more time together.

There is also a plan to build more university hotels, to encourage students to interact with the opposite sex.

But academics were sceptical about the success of such policies in halting a trend towards a burgeoning number of elderly with no family support network.

"Singlehood is a function of modernisation and urbanisation. And there is nothing much that government can do to arrest this," political scientist Ho Khai Leong told the Straits Times newspaper.

Statistics released on August 31 put the Singapore population at 4,017,733, up almost one million on the 3,047,132 head count of 10 years ago.

The non-resident population more than doubled over that period to 18.8 percent of the population.

There was also a sharp jump in the number of permanent residents, leaving Singapore citizens to account for less than 75 percent of the population.

In his recent National Day address, Prime Minister Goh Chok Tong described the high number of unmarried women and the small families of those who are married as "grave problems," and said Singapore needed to prop up its talent pool with foreigners.

One sociologist, Tan Ern Ser, told the Straits Times that a rising number of unmarried elderly people may not be an enormous drain on society as they are likely to be "healthier, wealthier and have more friends than present senior citizens."

However, sociologist Paulin Straughan argued that if the young remain unmarried "they may be able to prepare financially for the day they have to check into a home, but for Singapore to continue we have to have a next generation to develop the society."