A dormitory operator who forcibly confined 20 workers in a locked room has been given a stern warning by the Ministry of Manpower (MOM).

The workers' employer will also be barred from hiring new foreign staff pending a police investigation, the ministry said yesterday.

It said it "picked up" a Facebook post on the incident by migrant workers group Transient Workers Count Too (TWC2) on Tuesday.

TWC2 said it had received a distress call about workers being locked inside a room at the Joylicious dormitory in Tuas since at least 10.30am on Monday.

Workers who wanted to leave had to ask a security guard to unlock the door, which could take 30 minutes, the group added.

"This is an unacceptable and dangerous way to do things. What if a fire breaks out in the block?" it said.

Later that day, the workers were moved to a bigger room with an attached bathroom, but with the door still locked, TWC2 said in a separate post, and urged the authorities to act.

The police arrived at around 8pm, and the door was opened, TWC2 said in a third Facebook post.

The ministry said it immediately deployed inspectors to the dormitory after it picked up TWC2's initial post. It found the 20 workers in a warehouse with an attached toilet.

Investigations confirmed that the dorm operator had confined the workers on Monday with their employer's agreement.

"The reason given by the operator was to prevent them from moving around after a close contact was confirmed positive for Covid-19," said MOM.

"The dormitory operator was advised that it is unacceptable to forcibly confine the workers to their room."

The dormitory's manager, who wanted to be known only as Mr Thng, declined to comment.

The ministry noted that there is an established channel for TWC2 to raise cases of workers who may need assistance. "In this instance, TWC2 published the post on Facebook without notifying MOM," it said, urging members of the public to alert it to such incidents so it can respond quickly.

TWC2 vice-president Alex Au told The Straits Times last night it had informed the Migrant Workers' Centre (MWC), which has been the key interface for non-governmental organisations such as TWC2 with MOM for the past month, about the case on Monday.

MWC chairman Yeo Guat Kwang said on Tuesday it was notified about the case by TWC2 on Monday.

"As per our normal practice in cases such as this one, we alerted the enforcement unit of MOM about the case," he added.