Polling stations opened across Singapore on Friday for a snap election called by Prime Minister Lee Hsien Loong amid an economic slowdown.

Opposition candidates, who are contesting all districts for the first time, are hoping to gain enough seats in parliament to establish a two-party system after more than half a century of overwhelming control by the People's Action Party (PAP).

Tens of thousands of Singaporeans had attended opposition rallies in an intense nine-day campaign dominated by immigration, the high cost of living, and the plight of poor and elderly citizens left behind in the island's rapidindustrialisation.

Some 2.46 million citizens are eligible to vote for 89 members of parliament in Singapore's first election since the death of independence leader Lee Kuan Yew, the prime minister's father, in March.

During the campaign, the opposition used social media aggressively to countergovernment controlof newspapers and broadcast stations.

The PAP was stunned in 2011 when its share of the popular vote fell to an all-time low of 60 percent, but it retained 80 seats thanks to a block-voting system in most of the island.

The PAP's main rival, the Workers' Party, held seven seats, the most ever won by the opposition since Singapore became a republic in 1965.

Eight smaller parties also fielded candidates in Friday's polls.