To the average passer-by, the man in a striped shirt loitering in the open-air area next to Woodlands MRT station on Saturday afternoon was just one of many other people who appeared to be waiting for someone.

He was, in a way. As part of a team of six plain-clothes officers from the National Environment Agency (NEA), he was waiting to catch litterbugs in action as part of the agency's latest enforcement blitz conducted islandwide at more than 30 littering hotspots.

Working in teams of two, officers keep a lookout for offenders. Once someone is caught throwing rubbish on the floor, officers approach them and identify themselves as NEA officers before issuing a ticket.

There are about 92 littering hotspots in Singapore - mostly busy areas like MRT stations - and enforcement blitzes are conducted regularly.

Those caught littering for the first time face a $300 composition fine but will not be charged in court.

Recalcitrant litterbugs who are caught littering for the second time are slapped with a heftier fine and will be charged in court.

The latest enforcement blitz comes after NEA doubled penalties for littering on April 1 to $2000, $4000, and $10,000 respectively for the first, second as well as the third and subsequent court convictions under the Environmental Public Health Act.

The Straits Times saw at least five offenders caught between 4 and 5pm on Saturday, for littering and smoking in prohibited areas.