Of the infections, 964 were domestic transmissions, including 236 in the capital Bangkok, the epicentre of an outbreak that has spread to most of Thailand's 77 provinces.

The spike comes ahead of the major national Thai new year Songkran holidays, known for big street water fights that authorities have banned for a second year due to the pandemic.

Authorities have urged people to avoid unnecessary travel and reduce gatherings to help limit the outbreak, which includes the highly transmissible virus variant first identified in Britain.

"Right now, the situation is worrying. But we can manage it if everyone helps," senior health official Sopon Iamsirithaworn told a briefing.

At least 38 provinces have required visitors from risk areas to undertake a 14-day quarantine.

Nightspots such as pubs and karaoke bars in Bangkok and 40 provinces will be closed until at least April 23.

The managers of two entertainment venues in Bangkok, where many infections were reported, have been sentenced to two months in jail for COVID-19 violations, police said on Sunday.

Thailand has reported 3661 domestic infections so far this month, including 1294 cases in Bangkok, the highest amid the new outbreak.

That brings the national total to 32,625, with 97 deaths.

Australian Associated Press