SINGAPORE - Shoppers heading out to buy groceries at four popular wet markets will only be able to do so on alternate days depending on the last digit of their identity card or foreign identification card number from Wednesday (April 22), as part of measures to further limit crowds.

These four wet markets are Geylang Serai Market, Chong Pang Market at Block 104/105 Yishun Ring Road, and the markets at Block 20/21 Marsiling Lane and Block 505 Jurong West Street 52.

Those with an even last digit on their cards can visit these markets only on the even dates of the month, while those with an odd last digit can visit these markets only on the odd dates of the month, the National Environment Agency (NEA) said in a statement.

Persons who need assistance, such as the elderly and those with disabilities, can be accompanied by one family member or domestic helper, but one of their identification numbers must still meet the odd or even date entry restriction, NEA added, saying the elderly are still encouraged not to visit markets at peak hours.

The list of essential services will also be tightened. For example, hairdressing, barber services will be closed after Tuesday. Standalone outlets that sell only beverages, packaged snacks, confectioneries or desserts will also be closed.

From Wednesday (April 22), temperature screening will be implemented at all supermarkets and malls, and customers must provide particulars for contact tracing.

National Development Minister Lawrence Wong said at a media conference on Tuesday that these measures could be expanded to safeguard public health and stem the spread of the coronavirus in the community.

"We will start with wet markets and we may do this also in other popular areas like supermarkets in order to thin out the crowds and reduce transmission risk in these areas," he said.

Prime Minister Lee Hsien Loong said in an address before the press conference that some hot spots, such as popular wet markets, remain a problem as crowds make it difficult to practise safe distancing.

Mr Wong also urged Singaporeans not to exercise or go grocery shopping with others, including members of the same household.

"If you need to go out to buy food, to buy groceries, go out alone. Don't turn this into an occasion for a family outing. And if you need to go out to exercise, exercise alone and in your own neighborhood, don't travel out to exercise," he said.

More workplaces will also be shut, including consumer-facing businesses like food and beverage establishments, said Mr Wong, who co-chairs the multi-ministry task force tackling the Covid-19 outbreak.

The list of essential services to be tightened include:

- Hairdressing, barber services will be closed from April 21, 11.59pm

- Standalone outlets that sell only beverages, packaged snacks, confectioneries or desserts will also be closed from April 21, 11.59pm.

- Optician shops can operate by appointment only, and can no longer accept walk-in customers. Pet supplies stores and retail laundry services must close their physical stores, but are permitted to provide online sales and delivery.

- The number of businesses allowed to operate at their work premises, especially businesses that are less critical for daily living or to maintain essential supply chains, will be cut. The affected businesses will be notified by the Ministry of Trade and Industry and will have 24 hours upon notification to wind down their business operations completely.

About 20 per cent of Singapore's workforce continues to commute to work during the circuit breaker as they are in essential services. This proportion will be reduced to 15 per cent by reducing the number of services considered essential, said Mr Wong.

"So this will mean that all of us may face some degradation of services, or we may not be able to access F&B or certain services that we have become accustomed to," he said.

The move to tighten the list of essential services, first announced last week, is necessary as many of the local infections that occurred after the circuit breaker began had involved those working in essential services or who had family members that were, said Mr Wong.

"We do need our essential workers. We appreciate your contributions, but we have to reduce the numbers who are working."

Singapore is now two weeks into a circuit breaker aimed at keeping people home and containing the spread of the coronavirus. Non-essential services have been shut, while social gatherings and dining in at eateries have been banned.

There have been positive results thus far, but the battle against Covid-19 will be a prolonged one, and Singaporeans must continue to hunker down, said Mr Wong.

"We can take precautions like safe distancing and wearing of masks, but the best way to beat the virus is to stay home."

The tighter measures will remain in place until May 4, after which they may be adjusted as the circuit breaker continues for another four weeks, till June 1.

"If we see community numbers coming down to single digits, then we can consider gradually easing some of these measures," said Mr Wong.