SINGAPORE - Singapore voters headed to the polls on Saturday to elect their next president, which is largely ceremonial with custodial powers.

Voters started to cast their votes in the morning after the polling stations were opened from 8:00 a.m.

Incumbent president S R Nathan, who won the last two presidential elections uncontested in 1999 and 2005, also cast his vote at a polling station.

"I know the Singaporeans are sensible people. Whatever they are glad, they will do what's best for Singapore," he said.

There are four candidates in the first presidential polls since 1999. Candidates had to get a certificate of qualification from the elections department in order to run for president, with requirements that they must be people of integrity and have experience in a senior position or run a large enterprise.

The candidates, all surnamed Tan, had been campaigning ahead of the cooling-off day on August 26 since their nominations were confirmed on August 17.

Former Deputy Prime Minister Tony Tan, 71, is the obvious forerunner. He used to head government ministries such as finance, trade and ministry, and defense. He was also once the chairman and chief executive of United Overseas Bank (UOB), one of the largest local banks in Singapore.

He was most recently the deputy chairman and executive director of sovereign wealth fund -- the Government of Singapore Investment Corporation (GIC).

He had asked voters to choose who would best represent Singapore, at home and abroad, and who would have the right temperament, character and courage to remain calm at times of turbulence.

He said he could help Singapore weather the next financial and economic crisis if he gets elected.

The other candidates were Tan Cheng Bock, 71, a doctor and former lawmaker known for being outspoken on important issues; Tan Kin Lian, 63, a former chief of an insurance co-operative run by a labor organization; and Tan Jee Say, 57, who used to be a senior civil servant.

The polling stations will be closed at 8:00 pm on Saturday, with the result announcement expected shortly after that.