World leaders attending a summit in Phnom Penh will receive Cambodian-made watches from host Hun Sen, a noted fan of luxury timepieces.

The gift to VIPs at the Association of Southeast Asian Nations (ASEAN) and East Asian Summit gatherings has raised eyebrows in a country with no history of watchmaking.

US President Joe Biden and Chinese Premier Li Keqiang are among the guests over three days of meetings, which will cover the crisis in Myanmar and other regional issues.

The 25 tourbillion watches will be presented to delegates, said Hun Sen, who plans to wear one himself throughout the summit and at the upcoming G20 and APEC meets.

The watches feature matt grey faces emblazoned with "ASEAN Cambodia 2022" set in silver-coloured casing inscribed "Made in Cambodia", according to pictures on Hun Sen's official Facebook page.

Hun Sen -- who has ruled the kingdom for 37 years  and is Asia's longest-serving leader -- said the new watches "show the progress in science and technology of Cambodia."

The strongman ruler has been pictured in recent years wearing luxury Swiss watches worth hundreds of thousands of dollars.

Cambodian firm Prince Horology -- tasked with designing and assembling the pieces -- rejected suggestions that the items were overly luxurious, stressing that the watch faces were made of stainless steel.

Tourbillion watches are so-called for their intricate inner mechanism, seen from the outside, and patented around 200 years ago by a Swiss-French watchmaker.

While modern horology has made such designs obsolete, tourbillions are highly desirable to watch collectors with limited editions changing hands for hundreds of thousands of dollars.

"They are obviously highly decorated, highly polished," Prince Horology spokesperson Gabriel Tan told AFP.

The watches also feature "synthetic rubies", he said, that are "used to facilitate the watch movement."

All 25 were designed and assembled in Cambodia over the last 18 months, Tan said, declining to comment on their cost.

But in a country which boasts a rich cultural and artistic history, some questioned the gift.

"We are not Switzerland," said Cambodian rights activist Ou Virak, founder and president of the pro-democracy Future Forum group.

"It appears desperate, at least from the outside looking in," he told AFP, adding the gesture was unlikely to be looked on in a "positive" way.

"You have to really question who is making the watch," he said.

"I just hope that it is not another Chinese company made with a Cambodian stamp on it."

Prince Horology is part of the Prince Group of companies and is headed by Chen Zhi, a Chinese citizen granted Cambodian nationality in 2014, according to Radio Free Asia.

The group is among the largest conglomerates in the kingdom, with interests in banking, tourism, food and real estate.