Singapore police are investigating several karaoke bars for breaching coronavirus restrictions and have arrested 20 foreign women for alleged "vice-related activities" after an outbreak linked to the nightspots, authorities said.
The city-state has seen a spike in cases this week connected to the bars -- including a 10-month high of local transmissions on Wednesday -- and the number of infections in the cluster now stands at 87.
A staple of Singapore nightlife, the karaoke bars typically have blacked-out windows and are frequented by foreign female "hostesses".
Police said in a statement late Wednesday they were investigating three nightspots for breaching virus measures by allegedly providing "hostessing services".
Under current virus restrictions, the bars were only supposed to be operating in a limited fashion, providing food and drinks.
Twenty women, aged 20 to 34, from South Korea, Malaysia, Thailand and Vietnam, have been arrested for "suspected involvement in vice-related activities" at the bars, police said.
The first reported infection in the cluster was a Vietnamese hostess on a short-term visitor pass to Singapore who had been to many of the bars, officials said.
Another infection linked to the cluster was a passenger on a cruise, which was forced to return to Singapore earlier than scheduled Wednesday after the case was detected.
Singapore has so far suffered only a mild outbreak, but Health Minister Ong Ye Kung warned there was "potentially a very big cluster" emerging from the nightspots.
"We knew about cases like these happening in Korea's and Hong Kong's nightlife scene where people come very close together, some with hostesses, which led to big clusters," he told a press conference.
"We have never allowed such activities for more than one year. So for this to happen has been troubling and disappointing."
The government is encouraging people who have visited certain karaoke bars since June 29 to get virus tests, which they have promised will be confidential.