The death toll from a building collapse in southern Cambodia has risen to 36, with hopes dwindling of finding any further survivors.

Hundreds of soldiers and rescuers had worked through Saturday night using excavators, drills and power saws to clear concrete after a seven-storey hotel under construction in seaside Kep province crumbled to the ground on Friday.

At least a dozen bodies were found overnight, as well as another survivor, but on Sunday prime minister Hun Sen has announced the end of the rescue operation.

Officials had initially estimated that 30 workers remained trapped under the flattened structure. But provincial spokesman Ros Udong told AFP the number of injured and dead was higher than anticipated.

Rescuers carry a survivor out of the rubble on Saturday night. Photograph: Tang Chhin Sothy/AFP via Getty Images

Apart from the dead, Udong said, 23 survivors were pulled out. A statement from provincial authorities said at least 13 women and six children were among the dead.

In a news conference, Hun Sen said the couple who owned the building and hired the construction crew had been detained and sent to court to face charges. He did not specify the charges.

However, he defended the government response and said that no officials in Kep province would be fired. “Building collapses don’t only happen in Cambodia,” he said. “They happen elsewhere ... including in the United States.”

Kep provincial authorities said earlier that a committee had been formed to investigate the cause of the accident, which a provincial police official had said occurred when concrete was being poured on its top level.

Cambodia is undergoing a construction boom, with hotels, high-rises and casinos springing up under little regulatory oversight.

The tough – and often dangerous – work is undertaken by an estimated 200,000 construction workers, mostly unskilled, reliant on day wages and not protected by union rules, according to the International Labour Organisation.

Worker advocacy groups point to low safety standards that raise the risk of accidents at construction sites – which often serve as the temporary homes for the labourers and their families.

Worker Ei Kosal told AFP on Saturday that he, his wife and two other women were having a meal on site when the building collapsed.

Their two companions were crushed and immediately killed.

“I did not expect to survive ... it’s like I have just been reborn,” Kosal said while recuperating at the hospital.

In June, 28 people died after the collapse of a building under construction in Sihanoukville, a beach town flush with Chinese investment as Cambodia seeks to make it the “New Macau”.