A building under construction northwest of the Saudi capital has collapsed killing four workers, and leaving up to 50 workers trapped under rubble, officials said.

The collapse on Monday happened at a convention centre being built at Qassim University based in Buraida, a city 360km from Riyadh.

At least four people were injured in the incident, according to a statement by the civil defence authorities, which said 50 workers were working on the site at the time of the collapse. 

Bandar al-Roshodi, the university spokesman, told Saudi television news channel Al-Ekhbariya that the workers were mostly from Pakistan.

Roshodi told the AFP news agency that the search effort was ongoing and there was a possibility more survivors would be found.

"We have hope, God willing," he said.

Pictures from the scene showed a sprawling but low-level construction site, where many steel support rods had collapsed along with other parts of the structure.

The governor of Qassim province, Prince Faisal bin Meshaal, visited the collapsed building to inspect the scene.

Source: Agencies