Election officials in Singapore have ordered a recount of the presidential vote because results show a razor-thin difference between the two leading candidates.

Officials say there is less than a two percentage point difference between Deputy Prime Minister Tony Tan and medical doctor Tan Cheng Bock.

Singapore's election department did not say how many votes the two candidates got in Saturday's polling.

The election is seen as a referendum on the ruling People's Action Party – PAP-, which has led the city-state since 1959.

Tony Tan was backed by most of the political establishment, while Tan Cheng Bok is a former ruling party lawmaker who openly courted the opposition.

Singapore's presidency is largely a ceremonial position, but Saturday's election attracted four candidates.

Current President S.R. Nathan won two 6-year terms unopposed.