BANGKOK: Thailand added more measures on Thursday to arrest its biggest coronavirus outbreak yet, including a nationwide requirement to wear masks in public and a ban on dining at restaurants in and around its capital.

Authorities reclassified Bangkok and five provinces as highest-controlled zones. There are 46 others with broad restrictions after a third COVID-19 wave that has seen more than half of the country's overall infections this month alone.

Masks are widely worn in Thailand but the order to make them mandatory comes just a few days after Prime Minister Prayuth Chan-ocha was fined $190 for failing to wear one during a meeting.

Parks, gyms, cinemas, bars, restaurants, day-care centres and schools have been closed in Bangkok, the outbreak epicentre, and non-essential travel from the capital is being discouraged.

Public transport is still operating and malls remain open, but for shortened trading hours.

"This is not a lockdown, not a curfew, but we are asking for your cooperation," coronavirus taskforce spokesman, Taweesin Wisanuyothin, told a briefing.

The finance ministry on Thursday slashed its forecasts for economic growth and tourist arrivals because of the outbreak.

A total of 34,707 coronavirus cases and 94 deaths have been reported during April alone, bringing the infections total to 63,570, with 188 fatalities.

There were 1,871 new cases and 10 deaths reported on Thursday.

The outbreak includes the highly transmissible B.1.1.7 variant blamed for driving the contagion in many countries.

Thailand has yet to start its mass immunisation drive but has stepped up efforts to secure supplies to add to 2.5 million doses it has received from Sinovac Biotech and 61 million shots of AstraZeneca's vaccine to be produced locally.

The government is looking to Sinopharm, Moderna, India's Bharat Biotech and Johnson and Johnson as more sources, Taweesin added, with the aim of inoculating 70% of the population.

It was in talks last week to buy Pfizer's vaccine, and Russia's Sputnik V.