A team of officials will launch an investigation to pinpoint why there is an acute shortage of face masks, Prime Minister Prayut Chan-o-cha said on Wednesday.

The team will check shops and scrutinise the whole supply chain to detect whether and where the masks are being hoarded. The shops will be asked where they ordered their masks and if they received them. If the factories delivered fewer than ordered, the factories would have to explain, said the premier.

Gen Prayut said more than a million masks a day should be in circulation. If the masks are sold through proper channels and shops get what they have ordered, there should not be a supply problem.

Of the total number of masks produced per day, about 300,000 go to the Public Health Ministry for distribution to medical workers in hospitals and to shops affiliated with the Government Pharmaceutical Organisation (GPO).

The team will track where the remaining 700,000 to 800,000 masks end up. The government is supervising production in factories while the team will audit factory accounts to see who placed orders and where the masks were delivered.

The price of masks is capped at 2.5 baht. However, similar masks are sold at higher prices overseas. The prime minister insisted the price will remain firmly under control. The government said it also had to be fair to the factories.

"At the same time, we cannot allow the price to be jacked up," he said.

Prime Minister's Office Minister Tewan Liptapallop said the government is spending the 2 million baht donated by His Holiness the Supreme Patriarch to buy about 800,000 masks for monks.

Monks, particularly those in Bangkok temples, are considered at high risk of contracting the virus as they go out collecting alms and come into close contact with people.

Meanwhile, people queued up as early as 4am on Wednesday to snap up masks and sanitising gel at the GPO-affiliated shop in the government complex in Bangkok.

A chemist at the shop said each customer is restricted to 10 masks a day. Each mask is priced at one baht. He said the shop receives limited supplies of masks and gel.