Four people were injured this morning as the ground floor of a Chinese-owned garment factory in Takeo province partially collapsed into a water-storage unit below, according to local police.

Bati district police chief Ngann Sari said the accident, which happened around 9:30am, only caused minor injuries. The four injured were sent to the district hospital.

"We are still investigating the reason why the floor collapsed," he said.

A 20-by-40-metre water-storage area is located below the factory floor.

Nam Sorporn, Bati district deputy police chief, said a net underneath the floor helped to limit the damage, which may have been caused by faulty construction.

"The floor has collapsed in some parts while the workers were working, but it has not fully [collapsed into the water] because a net underneath firmly supported it. However, we can still initially conclude that it was caused by construction not in accordance with technical standards, or it could also have been caused by overloading," Sorporn said.

While police said no one remained unaccounted for, a representative from the Coalition of Cambodia Apparel Workers' Democratic Union (C.CAWDU) has claimed that 100 workers are missing.

Sari named the factory as Nishiku Enterprise, located in Bati district's Putsar commune.

According to the Garment Manufacturers Association in Cambodia database, the factory employs 1,200 workers.

The factory manager could not be reached for comment.

In May 2013, an overloaded and illegally built storage level at the Wing Star Shoes factory in Kampong Speu province collapsed, killing a teenager and a 22-year-old.