Islamabad  - At least eight people were killed and 14 injured when an apartment building collapsed in the southern Pakistan province of Sindh early Thursday, officials said.

The five-storey building in Sukkur, 375 kilometres north-east of Sindh's capital Karachi, came down around 3 am local time, city mayor Nasir Hussain Shah said.

"Eight people have been confirmed dead and 14 more are injured. Some of the wounded are in critical condition," he said.

Rescuers Thursday were trying to reach three people believed buried under the rubble.

Shah said substandard material or a faulty design of the building might have caused the collapse.

The building had 20 apartments but only five were occupied. (dpa)