The death toll has risen to nine from a blast at a steel plant in Inner Mongolia Autonomous Region, with one other person still unaccounted for as rescue efforts continue, local authorities said on Tuesday.

The explosion took place at 3.03pm on Sunday at a plate plant of Baogang United Steel in Baotou City, according to the on-site emergency rescue headquarters.

Previous reports show that the blast originated from a 650-cubic-metre saturated water and steam spherical tank.

Verification of the missing person is ongoing.

Previous reports indicated that 84 people were injured and hospitalised following the incident.

The Work Safety Commission under the State Council is overseeing an investigation. (Xinhua)