Seventy-three people have been caught on camera in the act of throwing litter out of high-rise blocks since the authorities installed surveillance cameras in housing areas.

The figure includes two nabbed during a small pilot trial in 2011, the National Environment Agency said. Since August 2012, the agency has deployed its surveillance cameras 880 times in 581 high-rise littering hotspots, which has helped address the problem in 81 per cent of these places.

Prior to the scheme, the agency had prosecuted just 42 people for the offence in a decade.

There are thousands of complaints about high-rise littering a year, Environment and Water Resources Minister Vivian Balakrishnan told Parliament in May this year, and suggested that penalties - a fine of up to $1,000 for first-time offenders - may have to be reviewed.

In 2013, the areas with the most feedback about high-rise littering were Sims Drive, Lorong 1A Toa Payoh and Dover Crescent.

"Surveillance cameras have been deployed at these areas and NEA is monitoring the situation," an NEA spokesman said.