Hungary's foreign minister tested positive for coronavirus in Thailand, the kingdom's health minister said Wednesday, a day after he jetted in from a meeting with Cambodian premier Hun Sen.

The confirmed case left the Cambodian strongman facing the prospect of a period in quarantine, as well as a test for the contagion.

Peter Szijjarto flew into Phnom Penh Tuesday for a one-day official visit to sign agreements on civil aviation, agriculture and water management, as well as reopening an embassy after a 25-year hiatus.

On Tuesday night, he arrived in Bangkok and was swiftly taken to hospital after testing positive for the virus on arrival.

The test "showed he has COVID-19, but he didn't have any symptoms", Thailand's health minister Anutin Charnvirakul told reporters, after he visited Szijjarto at Bamrasnaradura Infectious Disease Institute on Wednesday.

"His entourage all tested negative."

During his Cambodia visit, Szijjarto was pictured with Hun Sen at a meeting where neither appeared to be socially distancing or wearing a mask.

Neither Peter Szijjarto (left) nor Hun Sen (right) wore a mask when they met
Neither Peter Szijjarto (left) nor Hun Sen (right) wore a mask when they met AFP / STR

He also met his Cambodian counterpart and shook hands with a coterie of other ministers.

All of those people would now be tested and quarantined, according to Phnom Penh's foreign ministry.

"The leaders and all officials who met and had direct contact with the delegation during the visit will be tested for Covid-19 and quarantined in accordance with the ministry of health's advice," Cambodia's Foreign Affairs Ministry said in a statement.

Szijjarto's scheduled meetings in the Thai capital were cancelled, and an extra plane was ordered from Hungary to transport him home, separately from his staff.

The Hungarian embassy in Bangkok did not immediately respond to requests for comment.

Hun Sen, a staunch ally of Beijing, spent the early weeks of the pandemic refusing to wear a mask or close Cambodia's borders to China.

But as cases surged across Europe and the US, the kingdom barred foreign tourists -- though never those from the Chinese market -- and Hun Sen changed his tune, urging the public to don masks.

The country has emerged mostly unscathed from the virus, registering fewer than 300 cases and no deaths.