Singapore marks its 50th anniversary on Sunday celebrating a remarkable transformation from colonial backwater to regional powerhouse, but analysts say the festivities are unlikely to silence rumbling discontent ahead of expected elections.

The nationalistic celebrations are the high-point of a year of jubilee events and will be marked with a huge military parade, fireworks display and video tribute to late founding father Lee Kuan Yew, whose death in March prompted a national outpouring of grief.

More than a quarter of a million people are expected to take to the streets to attend the commemorations, reflecting the widespread pride felt by many residents at the city-state's achievements over the past half century.

But behind the highly choreographed events, the opposition is keen to tap into voter anxiety ahead of elections expected in September and pressure the government to ease strict political controls credited with keeping the ruling People's Action Party in power.

Singapore's birth as a nation state came on August 9, 1965, when it was ejected from the Malaysian federation following a stormy two-year union.

It has since gone on to surpass far larger neighbours Malaysia and Indonesia in terms of development and military power.

And although several metrics, such as home ownership of more than 90 percent and per capita gross domestic product of $56,284 in 2014, put Singapore among the most advanced societies in the world, critics say its success has come at a steep cost.

The recent jailing of teenager Amos Yee for insulting Christianity in a video tirade against Lee, as well as a defamation suit against an activist who accused the current prime minister of misusing state pension funds, have been held up as examples of the government's intolerance for dissent.

- Feel-good factor -

Analysts have widely predicted that Lee's son, Prime Minister Lee Hsien Loong, 63, will call snap elections for September 12 in the hope of harnessing the celebratory mood and extending the PAP's uninterrupted five and a half decades in power.

But the party, which suffered significant losses in 2011 elections, will have to contend with a series of voter gripes, including the high cost of living, immigration policy, rising healthcare costs and one of the widest incomes gaps in the world.

Singapore's low birth rate, coupled with its rapidly greying population, prompted the government to liberalise immigration policy in the mid-2000s, with the population surging from 4.17 million in 2004 to 5.47 million last year -- 40 percent of them foreigners.

But an influx of skilled and educated migrants has caused significant tensions. Educated, middle-class Singaporeans feel the newcomers are taking jobs and housing.

Immigration policy was blamed for the PAP's weakened showing at the last election, when the opposition Workers' Party wrested a five-seat constituency from the PAP for the first time.

It was the PAP's worst ever electoral performance, securing 60 percent of all votes cast, although a system of electing MPs in teams ensured it kept 80 of the 87 seats.

The opposition later extended its gains with two by-election wins.

Lee has since taken steps to arrest the dip in his party's popularity.

The government has invested billions of dollars in building new public housing flats and metro lines, while curbing the intake of foreign workers.

Michael Barr, an associate professor of international relations at Flinders University in Australia, said the government was hoping the outpouring of grief over Lee's death and the nationalistic fervour surrounding the anniversary celebrations would give it a boost at the polls.

"The PAP clearly judges that between the death of the older Lee... and the anniversary celebrations, that there is going to be a big fillip to the government in the election," he said.

However, Eugene Tan, an associate law professor at the Singapore Management University, said the government would be unwise to count too heavily on the boost the celebrations may provide.

"There will no doubt be a feel-good factor about the golden jubilee celebrations going into the general election but I am not sure it will be a game-changer," he said. afp