The Singapore Food Agency (SFA) has suspended the licences of two caterers after 39 people in two separate cases suffered from gastroenteritis recently.
Those affected in the cases on Aug 31 and Sept 2 became ill after consuming food from Mum's Kitchen Catering and Cherish Delights.
In a joint statement on Wednesday, the Ministry of Health (MOH) and SFA said they were investigating the incidents.
Three people were hospitalised, and while two of them have been discharged, one is still in hospital in a stable condition, SFA and MOH said.
In the light of the incidents, SFA suspended the licence of Mum's Kitchen Catering on Tuesday, and that of Cherish Delights on Wednesday. The licences are suspended until further notice.
Food handlers working in the caterers' premises are required to re-attend and pass the Basic Food Hygiene Course before they can resume working.
The same applies to food hygiene officers at the two premises - they must re-attend and pass the Food Hygiene Officers Course.
MOH and SFA said the two premises, as well as the utensils and equipment, need to be cleaned and sanitised.
"Food safety is a joint responsibility. SFA would like to remind food operators to observe good food and personal hygiene practices at all times," the statement said.
A spokesman for Mum's Kitchen Catering said yesterday that the caterer "deeply regrets the inconvenience caused to all its customers".
She said that the caterer is investigating the matter and has "taken immediate steps to review the whole supply chain process and practices".
"We have also requested our external food consultants to audit the entire supply chain and food processes once again.
"The SFA and MOH have also visited our premises and we are cooperating with them to investigate the cause of the incident," she said.