Supermarket operators have assured customers that there are sufficient stocks of fruits and vegetables in store, reminding them to buy only what they need.

The announcements by FairPrice, Sheng Siong and Dairy Farm International retail group, which owns Cold Storage and Giant, follow the temporary closure of Pasir Panjang Wholesale Centre.

The wholesale centre is closed for three days - from yesterday to tomorrow - for cleaning and disinfection after Covid-19 cases were detected among workers and visitors. It is expected to reopen on Thursday at 3pm.

The Health Ministry had identified 82 cases in the cluster as at yesterday night.

Of the cases, 76 are workers at the market, three are trade visitors and three are household members of cases.

FairPrice chief executive Seah Kian Peng said in a Facebook post that the supermarket gets supplies directly and has its own fresh food distribution centre.

However, the chain said it has increased the supply of fruit and vegetables to its stores islandwide while reminding customers to "only buy what they need".

It is already seeing a 10 per cent to 15 per cent increase in demand for fruit and vegetables compared with last week.

A spokesman for the Dairy Farm International retail group said it has not seen a surge in store traffic.

"Our supplier base is diversified to ensure sufficient supply across our stores, and we would like to assure customers that our stores have been minimally affected by the closure of the Pasir Panjang Wholesale Centre," added the spokesman.

Similarly, in a Facebook post on Sunday night, Sheng Siong said it is "working hard to ensure that all our stores remain well stocked with timely deliveries of fresh vegetables and fruits".

Singapore Fruits and Vegetables Importers and Exporters Asso-ciation chairman Tay Khiam Back said some suppliers and vendors would inevitably be affected by the closure of the wholesale centre.

He said: "The mid-to bigger-sized suppliers usually have warehouses outside of Pasir Panjang Wholesale Centre, so they would not be that badly affected. But smaller suppliers who only have facilities at the wholesale centre would have to close for three days."

He added that the closure has created some inconvenience for suppliers and vegetable vendors as the news reached them only on Sunday afternoon.

Some affected sellers, like Aw Guan Hong Vegetable Wholesaler, are planning to close their shops for a few days until the whole-sale centre reopens.

Aw Guan Hong has its office in the wholesale centre but runs market stalls as well.

Mr Mervyn Wong, manager of online retailer MarketFresh, said: "We get our supplies from the vendors at Tiong Bahru market. We have stopped selling vegetables on our website until the vegetable vendor resumes business.

"For now, he will be closed from Tuesday to Thursday."

While Pasir Panjang Wholesale Centre has a large concentration of wholesalers in one location, there are many other smaller warehouses and major supermarket chain-owned distribution centres around Singapore.

Some suppliers also import produce directly from overseas.

Pasir Panjang Wholesale Centre, which is located in the south-west of Singapore and spans about 15ha, handles about 30 per cent of Singapore's fruit imports and 50 per cent of vegetable imports, the Singapore Food Agency said on Sunday.

Professor Teo Yik Ying, dean of the Saw Swee Hock School of Public Health at the National University of Singapore, said workers there could have been ex-posed to and infected by Covid-19 elsewhere.

He said: "This is the reality with the highly transmissible Delta variant, that people could be exposed in many settings, and subsequently spread the virus to people in the same households or in the same workplaces."

Prof Teo added that the three-day closure at the wholesale centre would be "modestly useful" to stop further transmissions for the time being.