Hundreds of Indonesian workers protested against conditions at a Chinese-funded nickel-processing plant where an explosion killed at least 18 people and injured dozens more over the weekend.

The accident occurred last Saturday as workers repaired a furnace at a plant owned by PT Indonesia Tsingshan Stainless Steel (ITSS) in the Morowali Industrial Park on Sulawesi island.

Images seen by AFP showed hundreds of workers taking part in the protest outside the complex.

Demonstrators gave a list of 23 demands to management, according to a letter sent to police by unions representing the workers.

The demands included that smelters be better maintained, health clinics be improved to deal with emergencies and Chinese workers be required to learn the Indonesian language.

"No production is worth a life!" protesters shouted through loudspeakers, video footage of the demonstration showed.

Chinese among the dead

Thirty people are being treated in hospital for their injuries after the blast, according to police.

Dedy Kurniawan, a spokesperson for Morowali Industrial Park, told AFP that the company had "done what they (the protesters) demanded two days ago", without specifying which demands had been met.

Chinese foreign ministry spokesperson Mao Ning said Wednesday that eight Chinese nationals were among the dead, and that Beijing was "extremely saddened" by the accident.

Tsingshan Holding Group, the world's biggest nickel producer and China's biggest stainless steelmaker, holds a majority stake in ITSS.

ITSS is a tenant in the industrial park, which is also majority-owned by Tsingshan along with local partner Bintang Delapan.