Is Singapore's prized social stability under threat?

A rare incident of rioting in Singapore over the weekend has raised questions about social harmony in the wealthy Southeast Asian nation that has been built on a reputation of stability and prides itself on a long history of racial cohesion.

The underlying cause for the violence late Sunday, which was triggered by a fatal road accident that killed an Indian national, appears to be the festering grievance among low-wage foreigners.

'Poor people, whether foreign or local, are constantly reminded of their conditions in a city with obvious wealth; frustration is inevitable. The riot was obviously a 'blowing off steam' of pent-up frustrations and felt social isolation,' Chua Beng Huat, head of the Sociology Department at the National University of Singapore, told CNBC.

Singapore has one of the biggest wealth gaps in the developed world. Its Gini coefficient - which measures the degree of inequality within a country where zero is complete equality and one is maximum inequality - rose to 0.478 last year, the highest among advanced economies, apart from Hong Kong.

( Read more: First riot in 40 years rocks peaceful Singapore)

Chua said while the single incident should not be blown out of proportion, the risk of subsequent outbursts cannot be ruled out.

'When you have tens of thousands of people with relatively same sentiment crowded into a limited space, mass behavior should be expected anytime; the risk is perpetual,' he said. Little India, city's ethnic Indian district where the riots took place, is a popular hangout for South Asian workers during the weekends.

Migrant workers have been an integral part of Singapore's $274 billion economy, enabling a construction and infrastructure boom over the past two decades that has transformed the tiny island nation into a world-class city.

There are around 1.3 million foreign nationals in Singapore whose population is 5.4 million, many of whom are employed in low-paying labor-intensive or services jobs that are shunned by most locals. More than 300,000 work permit holders are employed by the construction industry alone.

According to the non-profit organization Transient Workers Count Too (TWCT), the city's foreign workers have long been victims of mistreatment, from being denied proper medical treatment by their employers to failing to receive their promised salaries.

'It is not possible at this stage to say what part these feelings played in the explosion of random violence,' the organization said on its website earlier this week.