Prime Minister Prayut Chan-o-cha has ordered authorities to review privileges given to foreign diplomats and military personnel after an Egyptian soldier and the daughter of a diplomat who tested positive were exempted from quarantine.

He ordered the Centre for Covid-19 Situation Administration (CCSA) to review Covid-19 restrictions to find loopholes in disease control measures.

Besides diplomats and their families, flights from foreign countries, including military aircraft, will have to follow these measures, Prayut said.

The prime minister on Tuesday apologised to the public for an incident in which an Egyptian soldier confirmed to be infected with Covid-19 was found to have visited shopping malls in Rayong province.

As a result, 1,889 local people who went to the same malls as the Egyptian who tested positive now face home quarantine.

"This incident should not have happened. It's a lack of discipline, showing disregard for the rules and the common good," Prayut said.

"It was a lack of responsibility and failure to keep a promise. But they [the Egyptian delegation] still went outside. I've told the Foreign Affairs Ministry to discuss the matter with the [Egyptian] ambassador to make sure this will not happen again," Prayut said.

"All flights will not be allowed into Thailand temporarily until the problems are fixed. This problem has affected public confidence and safety. The government will do its best. Give the CCSA some time to fix the problem," Prayut said.

However, there was no need to put the country back under a lockdown, he added.

Prayut also expressed concern that many Thais and business operators are lowering their guard, adding that he has ordered officials to ensure that premises, particularly nightlife venues, strictly follow health measures.

Taweesilp Visanuyothin, spokesman of the CCSA, said on Tuesday that in future arriving foreign diplomatic staff and their families would have to stay for 14 days at "alternative state quarantine" facilities that the government would arrange. 

Privileged visitors are people the prime minister or an emergency state supervisor have invited to the country. Business reps under special arrangements plan on only short stays. Both categories have been allowed in since July 1.

The diplomat - the Sudanese attaché whose daughter tested positive - and family had been staying in Bangkok at the One X condominium building, which has 329 rooms -- 200 of them occupied. About 70% of the residents were foreigners, Dr Taweesilp said.

Seven people were at high risk of infection -- the Sudanese girl's parents and younger sister, a limo driver, two airport van drivers and a Sudanese embassy official.

Fifteen other people who used the same elevator the family used were deemed at low risk of infection, he said. The family and drivers would be tested today.