Chinese authorities have said dozens of victims remain trapped inside a building in the city of Changsha that partially collapsed on Friday in central China's Hunan Province.

Resucers worked through the night to shift debris, pulling five people out of the rubble alive on Saturday morning.

Changsha's mayor said 23 people remained trapped while another 39 were uncontactable and could also be inside.

The building housed a small cinema and a guest house.

It's unclear why the structure suddenly caved in. State media said some tenants had recently made structural changes to the premises.

Chinese President Xi Jinping on Saturday ordered relevant departments to make all-out efforts to search and rescue victims, treat the injured, and properly handle follow-up matters.

He added that rescue operations should be carried out in a scientific manner to prevent secondary disasters, ordering a full investigation of the incident.

The collapse took place at 12:24 Friday in Wangcheng District in the provincial capital Changsha. 

Building collapses are not uncommon in China due to shoddy construction and lax safety standards.

As the collapses of self-constructed buildings across China have caused heavy casualties in recent years, Mr Xi instructed authorities to launch a special nationwide campaign on the safety of self-built buildings, so as to ward off major accidents, ensure the safety of people's lives and property, and maintain social stability.

ABC/wires