Dengue cases in the first five months of this year alone have hit a high of 7,000, more than the 4,632 cases in the whole of last year, and 5,330 in 2011.

Construction sites only comprise about 5 per cent of mosquito breeding grounds here, the National Environment Agency revealed on Saturday, compared to up to 70 per cent for homes.

But this has not stopped contractors and workers from playing their part in ending the dengue outbreak.

This weekend, workers will scour more than 150 construction sites to destroy breeding grounds, in an effort by the Singapore Contractors Association Limited (SCAL).

For example, they will level ground depressions at sites, where stagnant water may collect and attract mosquitoes.

Minister for the Environment and Water Resources Vivian Balakrishnan warned last month that Singapore was facing "a full-blown epidemic", that would continue to grow and possibly hit 1,000 infections a week at its peak.

But there have been no dengue deaths this year, unlike in previous years. In 2005, 14,000 infections were recorded, killing 25, and in 2007, 24 out of the 8,700 who caught dengue died.