For years Singapore has marketed itself as one of the world's most open economies and welcomed expats especially to the finance and banking sectors. Indeed it has even been called the Asian version of Dubai.

Now there are signs though that a small but growing group of people are unhappy that the influx of foreign workers is depriving some people of a decent career and they want to make immigration a key subject for next year's general election.

Between 2005 and 2009, Singapore's population surged by roughly 150,000 people a year to five million, among the fastest rates ever, with 75% or more of the increase coming from foreigners.  In-migration continued in 2009 despite expectations it would collapse because of the global recession.

The influx helped boost Singapore's economy in the short run by creating new demand for goods and services and developers built apartments and posh shopping centres for the new arrivals. Those though who want to see stricter immigration controls say that foreign workers have driven up real estate and other prices and made the city-state's roads and subways more congested exacerbating Singapore's gap between rich and poor.

Singapore, unlike many of its neighbours, has a reputation for reliable public services and minimal corruption. Its openness to foreign investment is one reason why gross domestic product is expected to rebound to 4.5% this year, according to the Asian Development Bank, from a contraction of 2.1% in 2009.

At the same time though, as an influx of skilled managerial class workers there has also been an influx of cheap unskilled labour and this is keeping wages down. 'Immigration is keeping our economic growth high but at what cost?' said Kenneth Jeyaretnam, the secretary-general of Singapore's Reform Party, a small opposition party founded in 2008.

Relying on foreign labour to help boost growth is unsustainable, according to Choy Keen Meng, an assistant professor of economics at Singapore's Nanyang Technological University. Even Prime Minister Lee Hsien Loong, has acknowledges that immigration may be getting out of hand.

Singapore though remains committed to a long term goal of increasing the population to 6.5 million, though it would do so by prioritizing high skilled residents as opposed to blue collar workers. Serious cuts to immigration could also generate a backlash from other interests such as real estate developers who rely heavily on foreign arrivals.