Singapore will impose fresh curbs on car ownership and improve public transport to tackle worsening congestion in the city-state, its transport minister said in comments published Tuesday.

Lui Tuck Yew said the current 1.5 percent annual growth in car ownership -- already down from 3.0 percent three years ago -- will have to be reduced further after January 2012 because Singapore has limited space for new roads.

"For the next three-year phase, it will not stay at 1.5 percent but it will have to come down," the Straits Times quoted him as saying. He did not give any details of the curbs, which the report said would be released later this month.

Singapore's public transport system is already the most modern in Southeast Asia but the minister vowed further improvements following public feedback about congestion on buses and trains during peak hours.

They include building more metro stations close to housing clusters and enlarging bus stops so they can accommodate more buses simultaneously.

Singapore controls car ownership through a quota system under which a car buyer must pay for a Certificate of Entitlement (COE), whose numbers are now capped at about 30,000 a year.

The reduction of car ownership growth is expected to further boost prices in the island nation, already one of the costliest places in the world to own a private vehicle.

The Toyota Vios, a popular compact sedan, now costs about Sg$90,000 ($70,000), more than half of which goes into buying a COE.

In addition to the quota system, car owners have to pay for entry into main highways and the central business district through an electronic toll network.

Official statistics show there were 945,829 motor vehicles in Singapore last year, including private cars, taxis and motorcycles. This was up 2.2 percent over 2009.

The local population, including citizens, permanent residents as well as foreign workers and their families, totalled 5.18 million as of June 2011, up 2.10 percent from the year before.

About 12 percent of Singapore's land area is now taken up by roads compared with 15 percent for housing, the Straits Times said.

Growing urban congestion was one of the biggest public gripes in May's general election in Singapore, which saw voter support for the ruling party dipping to an all-time low of 60 percent even though it won 81 of the 87 seats contested.