Mediacorp artistes are being investigated for possible breaches of safe distancing measures after a group gathered at a residence to celebrate actor Jeffrey Xu's birthday.

In response to queries from The Straits Times, the Ministry of National Development (MND) confirmed the probe, saying it was alerted to the incident.

"Investigations are ongoing in respect of possible breaches by the various parties," a spokesman said, without identifying the individuals implicated.

"MND and other government agencies take a serious view of such breaches and will not hesitate to take firm action against those who are found to have violated safe distancing measures."

Mediacorp celebrities Xu, Shane Pow and Terence Cao apologised on Wednesday via the broadcaster after photos of them apparently breaching Covid-19 regulations were posted on social media.

One picture, reportedly uploaded on Oct 3, showed 13 people standing close to one another, with Xu holding a cake.

No one was wearing a mask.

Under current Covid-19 regulations, social gatherings must be limited to groups of five outside residences. Households may receive up to five visitors at any one time.

From Monday, social gatherings in groups of eight will be allowed outside the home, and households may receive up to eight visitors.

A Shin Min Daily News reader had tipped off the Chinese-language publication - which ran a report on Wednesday - that Xu, who celebrated his 32nd birthday on Oct 3, had posted an Instagram story of a large gathering.

The attendees included other celebrities such as Jeremy Chan and Julie Tan, who are not managed by Mediacorp.

Mediacorp said in a statement to Shin Min that the three stars under its management - Xu, Cao and Pow - confirmed that they were at the gathering.

It said the three "deeply regret" their actions and apologised for their mistakes.

In an updated statement, Mediacorp said that 987FM deejay Sonia Chew was also at the gathering.

The broadcaster said that it takes safe distancing and Covid-19 regulations seriously, and reminded its artistes to follow such rules in both their professional and personal capacities.

Tan, who is managed by LNX Global, actor Li Nanxing's management agency, also issued an apology in a statement to The Straits Times.

She wrote: "I have made a mistake. I recognise the selfishness of my actions.

"Every citizen has a duty, every person has responsibilities. As a public figure, I was supposed to be a good role model, but I have failed."

• Additional reporting by Jan Lee