SINGAPORE - Mosquito breeding is on the rise ahead of the traditional peak season for dengue between June and October, Second Minister for the Environment and Water Resources Grace Fu said on Friday.

In response, the National Environment Agency (NEA) has stepped up checks on construction sites and warned of stiffer penalties for contractors should their work sites be located within an active dengue cluster.

Errant contractors may be given longer Stop Work Orders or prosecuted in court.

The NEA has inspected 7,700 work sites this year, as of last month - an 80 per cent rise on the same period last year.

It found mosquitoes breeding at 12 per cent of sites, up from 10 per cent last year. Aedes mosquitoes, which transmit the dengue virus, were found in 8 per cent of inspections.

Ms Fu urged contractors to step up their own efforts to eradicate mosquito breeding grounds within work sites. She was speaking on a visit to a work site in Sengkang operated by Tiong Seng contractors, which has had several workers infected by dengue this year.

Last year's dengue epidemic was Singapore's worst ever, infecting more than 22,000 people and killing seven.