Twenty-seven soldiers at Clementi Camp fell ill on Thursday, with some showing signs of food poisoning such as vomiting and diarrhoea.

The soldiers, mostly full-time national servicemen (NSFs), were hit by a highly contagious intestinal virus and they reported sick at the camp's medical centre on Thursday morning.

All of them had been in the camp from Wednesday.

Confirming the outbreak, the Defence Ministry said the servicemen were treated for symptoms of gastrointestinal disease and are now stable.

A Mindef spokesman said all of them had been discharged from the medical centre and they have since been given light duties. The cause of their illness is being investigated.

The spokesman added that the unit has taken precautionary measures to prevent the spread of the disease by "ceasing cookhouse operations, disinfecting dining and communal areas, and enforcing good personal hygiene practices".

After the outbreak, everyone in the camp was instructed not to drink the water or eat the food from the camp's cookhouse and canteen. Signs were put up in the toilets, reminding servicemen not to drink tap water. The Straits Times understands that in the interim, food and water from another camp are being delivered to the soldiers.

The last known gastrointestinal outbreak in an SAF camp took place in September 2013, when some 300 recruits at the Basic Military Training Centre fell prey to a contagious intestinal virus. Investigations found that the cookhouse premises and food handlers were not the source of infection. The food and water there also tested negative for contamination.

CHONG ZI LIANG, JERMYN CHOW