The Government is reviewing penalties against litterbugs, said Prime Minister Lee Hsien Loong at the launch of the annual Clean and Green Campaign on Saturday.

PM Lee pointed out that while most Singaporeans take pride in their environment and do not litter, there are a minority who litter, dirty tables at hawker centres and even abuse enforcement officers. "We must not condone such bad behaviour, or let it spread," he said.

Details of the review were not available. For now, those caught littering now would still face a composition fine of up to $300.

At the campaign launch at Serangoon Central, Mr Lee also said that Singapore's green plan - the Sustainable Singapore Blueprint - is being updated with new programmes such as building environmentally-friendly hawker centres and reducing carbon emission.

The Prime Minister also presented awards to two community development councils and five constituencies for their efforts to keep their estates clean and green, and appointed six gardening ambassadors to spread the community gardening drive.

The National Environment Agency, which spearheads the annual campaign, singled out 10 individuals as environment champions at the launch. They include a housewife who set up a Facebook account to start a litter-picking drive, a grassroots leader who checks on mosquito breeding,and a marine biologist who tracks the health of seagrasses in Singapore.