The city-state's ruling People's Action Party (PAP) has called an election more than a year early in a gamble that it can ride back into office on the feel-good factor of Singapore's 50th birthday on August 9.

Mr Lee's strong grip and dominant personality shaped Singapore into becoming a glittering regional financial powerhouse with a US$300 billion a year economy while he crushed political opposition and a free media.

Mr Lee died in March aged 91.

Prime Minister Lee Hsien Loong acknowledged at the time of his father's death that Singapore was at an "inflection point" and faced some of the same challenges of developing countries, citing an ageing society, generational changes and the need for economic transformation.

At the last poll in 2011 the PAP received 60 per cent of the popular vote, its worst showing since Mr Lee began turning a colonial backwater into a global trade and finance centre a half century ago.

Mr Lee's government has recently taken steps to slow the rate of foreign workers into the packed city and has given out more financial assistance to citizens for health care and housing.

In 2011 the PAP won 81 of 87 parliamentary seats.

A general election did not have to be called until 2017.

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