Phnom Penh, Jun 23 (AFP) The death toll in the collapse of a Chinese-owned building under construction at a Cambodian resort rose to 17 overnight, officials said Sunday, as rescue workers scrambled to find survivors buried under rubble.

The building went down before sunrise on Saturday in the casino-resort coastal town of Sihanoukville in southwestern Cambodia, a rapidly developing tourist hotspot awash with Chinese investment.

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.

The seven-storey building was nearing completion when it collapsed, reportedly trapping dozens in the deadliest such accident in recent years in Cambodia.

Preah Sihanouk provincial authorities said 17 people had died in the accident, with 24 injured, according to a statement sent to AFP.

Officials had earlier pinned the number of dead at seven.

More than 1,000 people including soldiers, police officers and medics worked overnight to search for survivors.

Rescue workers earlier pulled victims from a mountain of concrete, wood and twisted metal, some in body bags or with dislocated limbs.

An investigation into the cause of the accident has been launched, and Cambodian Prime Minister Hun Sen said negligence was to blame.

"The tragedy of the building collapse in Preah Sihanouk province is painful... for our nation, especially the families of those who lost" their lives, he said, announcing compensation of USD 10,000 each for the victims' households.

There was no confirmation of precisely how many people were at the building at the time of the collapse, though earlier officials said 30 people were feared trapped.

Around 50 workers would normally have been on the site at the time, Preah Sihanouk governor Yun Min said.

The building belonged to a Chinese national who rented the land from a Cambodian owner. The construction firm and contractor were both Chinese-owned as well.

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

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

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

Between 2016 and 2018, USD 1 billion was invested by Chinese government and private businesses in the Preah Sihanouk province, according to official statistics.

Cambodia, one of Southeast Asia's poorest countries, has notoriously lax safety laws and labour protections. Accidents are common at building sites. (AFP)

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