This campaign to improve the hygiene of markets, hawker centres, other eating establishments and public toilets is being brought back by the National Environment Agency (NEA).

All participating outlets and toilets that sign up for the voluntary programme will be given a 'Singapore's OK' sticker if they meet the criteria after being inspected by the NEA.

This criteria will be in addition to the basic hygiene standards that they should already be fulfilling, said Minister for the Environment and Water Resources Yaacob Ibrahim on Friday.

Reviving the campaign is timely as Singapore now faces a growing risk of being hit by the Mexican swine flu, he added.

Health Minister Khaw Boon Wan has said that the best precaution people can take against swine flu is to maintain a high level of personal hygiene, including washing hands properly, wearing a mask or avoiding crowded places when ill.

The Health Ministry on Thursday raised the alert level for the risk of a flu pandemic here a notch higher from yellow to orange on Thursday, just a day after upping it from green to yellow.

Singapore uses a five-colour alert system for the risk of a flu pandemic, rising from green to yellow, orange, red and the most serious, black. Each level calls for different measures, and corresponds to different levels of the global threat of a flu pandemic gauged by the World Health Organisation (WHO).

There are still no probable cases of swine flu here, but Singapore is raising the alert level in tandem with the WHO, which has lifted its alert level from Phase 4 to 5, just one step away from a pandemic.