PHNOM PENH • At least seven people died yesterday when an under-construction building owned by a Chinese company collapsed at a Cambodian beach resort, officials said, as hundreds of rescue workers searched for survivors in the giant rubble heap.

The building went down before sunrise in the casino-resort town of Sihanoukville in south-western Cambodia, a rapidly developing tourist hot spot awash with Chinese investments.

Four people have been detained in connection with the accident, including the Chinese building owner, the head of the construction firm and the contractor.

A Cambodian landowner has also been held at provincial headquarters for questioning.

"Now the death toll from the building collapse is seven," Sihanoukville city police chief Thul Phorsda said.

At least 23 people were reported injured - several critically - and at least three of the dead were Cambodian, including two workers and a translator.

Sihanoukville was once a sleepy fishing community before being claimed first by Western backpackers and then by wealthy Russians.

Chinese investment has flooded in in recent years, spurring a construction boom in a resort town known for its casinos that pull in mainland tourists.

There are around 50 Chinese-owned casinos and dozens of hotel complexes under construction.

Between 2016 and last year, US$1 billion (S$1.4 billion) was invested by Chinese government and private businesses in Preah Sihanouk province, according to official statistics.

Cambodia has lax safety laws and labour protections.

AGENCE FRANCE-PRESSE