Workers clawed back the rubble overnight as a grim-faced Cambodian premier Hun Sen visited the scene of the collapse in Sihanoukville, a beach town undergoing a Chinese investment bonanza.
The night was punctuated by grim processions of bodies on stretchers being carried to waiting ambulances.
On Monday morning, an AFP reporter saw a partially buried body, covered by a mosquito net to keep off flies in the searing heat, as the debris began to yield after 48 hours of excavation by hand, pneumatic drills and diggers.
"We don't expect any more survivors," a soldier who has manned the scene throughout told AFP, requesting anonymity.
Preah Sihanouk provincial officials put the death toll at 24, with a similar number injured.
Distraught relatives at a local hospital said around a dozen people were believed to be entombed in the concertinaed floors of the building, which collapsed before dawn on Saturday as dozens of workers slept.
"I lost my husband and my nephew," Khim Pov, 47, crying and hugging her daughter, told AFP while her son -- who was able to crawl out from the debris -- received treatment.
"I don't have any hope my husband has survived. The bodies being pulled out have been flattened."
Other survivors said they woke to a loud bang and managed to escape as the building folded in, leaving dozens of workers stranded on upper floors.
- Billion dollar town -
The once quiet fishing village of Sihanoukville has seen a Chinese construction boom driven by tourists to its dozens of casinos in recent years, with questions raised about the speed of development in a nation notorious for lax safety standards.
Three Chinese nationals and a Cambodian landowner have been held for questioning over the building collapse, which Hun Sen blamed on "carelessness" by the construction company.
The Chinese embassy in Cambodia, a strategically important country with ports and borders to other Mekong countries, expressed their condolences and backed a "thorough investigation" of the role of the three Chinese nationals and the cause of the accident.
There are an estimated 200,000 construction workers in Cambodia, most unskilled, reliant on day wages and not protected by union rules, according to the International Labour Organization (ILO).
Beijing is pouring investment into Cambodia as part of its behemoth Belt and Road initiative, a sweeping trillion-dollar infrastructure programme across Asia, Africa and Europe.
Around $1 billion was invested in the Preah Sihanouk province between 2016 and 2018 alone, and there are around 50 Chinese-owned casinos and dozens of hotel complexes under construction in Sihanoukville.