BANGKOK (REUTERS) - Thailand reported 1,390 new coronavirus cases on Monday (April 19), slowing slightly after a run of record daily highs, amid a new wave of infections that has seen a third of the country's cases recorded this month alone.

The new infections were down by a fifth from Sunday's record 1,767 cases. The coronavirus task force attributed this to measures to control the spread and requests for people to avoid travel and gatherings.

"Measures we have introduced for the next two weeks will reduce cases, travel and risky activities," Ms Apisamai Srirangsan, a spokesman for the task force, told a briefing.

Three new deaths were reported, taking total fatalities to 104.

Thailand's third wave of infections is its most challenging so far, reaching all 77 of its provinces as the country celebrated a long holiday.

The infections include the highly transmissible B117 variant of the virus and the majority of cases have been without symptoms.

Schools, bars and massage parlours have been closed until next month and alcohol sales banned in restaurants.

Of the 14,736 new cases this month, 3,615 have been in Bangkok, epicentre of the outbreak, and 146 medical personnel have been infected, the task force said.

Prime Minister Prayut Chan-o-cha is confident the current measures to prevent super-spreading events would contain the rate of infections, government spokesman Anucha Burapachaisri said on Monday.

"The government decided not to implement 'lockdown' and 'curfew' to avoid a larger impact to the public. Nevertheless, everyone is urged to strictly comply with the Covid-19 measures," he said in a statement.

The government said it would implement additional economic stimulus measures as appropriate.

Last week, Deputy Prime Minister Supattanapong Punmeechaow said this year's economic growth target of 4 per cent could be missed due to the new outbreak.