Health authorities in Thailand reported 9,635 new coronavirus cases on Monday, doubling the previous daily record set last week. Over 70% of Monday’s increase -- 6,853 cases -- came from prisons.

Thailand had about 7,100 cases including 63 deaths in all of last year, in what was regarded as a success story in containing the virus.

The capital, Bangkok, accounted for 1,843 of Monday’s new cases, with no signs of decline, said Taweesilp Visanuyotin, spokesperson for the government’s Center for COVID-19 Situation Administration. He said half of the city’s 50 districts have high rates of infection.

A health worker administers a dose of the Sinovac COVID-19 vaccine to a woman in Bangkok, Thailand, Monday, May 17, 2021. Health authorities in Thailand on Monday reported 9,635 new confirmed cases of COVID-19, a new daily high that brought the cumulative total since January last year to 111,082. Almost three-quarters of all cases were recorded since April 1, when Thailand's third coronavirus wave began. (AP PhotoAnuthep Cheysakron)

A health worker administers a dose of the Sinovac COVID-19 vaccine to a woman in Bangkok, Thailand, Monday, May 17, 2021. Health authorities in Thailand on Monday reported 9,635 new confirmed cases of COVID-19, a new daily high that brought the cumulative total since January last year to 111,082. Almost three-quarters of all cases were recorded since April 1, when Thailand's third coronavirus wave began. (AP PhotoAnuthep Cheysakron)

Despite no downturn in infections, restaurants in Bangkok and neighboring provinces were allowed on Monday to resume indoor dining until 9 p.m., with seating limited to 25% of capacity. Since May 1 they had only been allowed to provide takeout service.

Bangkok officials said closures would be extended for two more weeks for schools, entertainment venues, cinemas, fitness clubs and sports arenas.

The current wave was traced to nightspots in popular Bangkok entertainment districts. But 28 virus clusters have now been identified across 19 districts, including markets, slums, low-income housing and construction sites.

A health worker administers a dose of the Sinovac COVID-19 vaccine to a person in Bangkok, Thailand, Monday, May 17, 2021. Health authorities in Thailand on Monday reported 9,635 new confirmed cases of COVID-19, a new daily high that brought the cumulative total since January last year to 111,082. Almost three-quarters of all cases were recorded since April 1, when Thailand's third coronavirus wave began. (AP PhotoAnuthep Cheysakron)

A health worker administers a dose of the Sinovac COVID-19 vaccine to a person in Bangkok, Thailand, Monday, May 17, 2021. Health authorities in Thailand on Monday reported 9,635 new confirmed cases of COVID-19, a new daily high that brought the cumulative total since January last year to 111,082. Almost three-quarters of all cases were recorded since April 1, when Thailand's third coronavirus wave began. (AP PhotoAnuthep Cheysakron)

The Corrections Department announced that in the first half of this month, it conducted COVID-19 tests on 24,357 inmates in eight prisons, five of them in Bangkok, and about half tested positive.