More than 4,000 people have been apprehended at illegally operating nighttime entertainment businesses over the last seven weeks, the National Police Agency said Monday.

According to police, 635 cases of illegal activities have been uncovered after conducting on-site inspections of 56,699 businesses across the country from July 3 until Sunday.

Police said there were 3,566 people who violated the infectious disease control and prevention act. The rest were violations of either the food sanitation act or music industry promotion act.

The illegal operation of nighttime entertainment businesses has caused a public outcry as they continued to break the rules while increasing the risk of silently spreading the virus.

The Seoul Metropolitan Police warned on Wednesday that authorities were going to carry out field inspections to crack down on nighttime entertainment businesses operating illegally from Thursday through Friday in the city.

Despite the warning, police found 53 cases of illegal activities, along with 359 violators.

In particular, one of the violations was a pub that had already been busted in March for violating quarantine guidelines and faced a two-week shutdown order.

In another case, a business was caught transporting people by vehicle to a hidden place in another region where the illegal operation took place.

There were also instances of restaurants that operated as karaoke pubs behind closed doors after allowed business hours.

Police said they plan to apply strict measures by imposing criminal punishments to not only the business operators, but also visitors.

The official added that the police will continue to conduct intensive crackdowns on facilities operating in violation of the rules.

Under the highest social distancing measures, Level 4, the operation of what are known as nighttime entertainment facilities -- which includes clubs and private bars that provide paid drinking partners for entertaining -- is illegal. Level 3 guidelines force these businesses to close their doors after 10 p.m.

Amid the surging number of coronavirus infections, the Greater Seoul area has been under the Level 4 measures since July 12, while the rest of the country has maintained the Level 3 guidelines for nearly a month. 

By Kan Hyeong-woo (hwkan@heraldcorp.com)