A mountain of rubbish collapsed at a landfill in the central Philippines on Thursday, killing a 22-year-old woman andleaving more than 30people missing, authorities have said.

Rescuers pulled 12 injured sanitation workers from debris at the Binaliw Landfill in Cebu City, who were later hospitalised.

Many of the missing are believed to be workers at the landfill. The mayor of Cebu told news outlet ABS-CBN that it may be difficult to reach survivors because of the potential for further collapse.

The cause of the collapse is still unclear, but Cebu City councillor Joel Garganera said it was likely the result of poor waste management practices.

Some 300 people from various government agencies and civilian groups have been deployed to the privately-owned landfill. Several excavators, ambulances and fire trucks have also been seen on site.

"All response teams remain fully engaged in search and retrieval efforts to locate the remaining missing persons," Cebu Mayor Nestor Archival said in a Facebook post on Friday.

"This is not like other landslides that you can just excavate. If you pull from the top, the bottom is soft. Let's say there is a person there, when you get the debris, it might get worse," he said, ABS-CBN reported.

Cebu City councillor Joel Garganera said the incident may have happened suddenly, but was likely a result of poor waste management practices.

Operators had been cutting into the mountain, mining the soil, and then piling garbage to form another mountain of waste, Garganera told local newspaper The Freeman.

"It's not a sanitary landfill. It's already an open dumpsite," he said.

Families are waiting for updates on their loved ones trapped in the debris.

One Binaliw resident, Belen Antigua, told Rappler that her son had survived the landslide but she was still waiting for her other relatives to be found. Another said that families had been gathered at the landfill to look for their children since Friday morning.

"I could not understand my emotions. They said those trapped are calling for help, so there is a possibility that my brother is still there," Michelle Lumapas, whose brother works at the landfill, told ABS-CBN.

The Binaliw landfill is about 15 hectares (37 acres).

Landfills are common in major Philippine cities like Cebu, which is the trading centre and transportation gateway of the Visayas, the archipelago nation's central islands.