China's Supreme Court Wednesday ordered that people who neglect workplace safety should be "severely" punished, state media said, after the country's deadliest blaze in over a decade killed 120 people at a factory.

Last week's fire at the Baoyuanfeng poultry plant in the northeastern province of Jilin renewed concern over workplace safety. Local reports said only one door remained unlocked, impeding employees' escape.

"The Supreme Court issued a notice on June 12 requesting courts at all levels to deal severely with crimes that jeopardise manufacturing safety," the official Xinhua news agency reported.

The high court described several "particularly vile" scenarios, including "discovering safety risks but not eliminating them, not guaranteeing basic work safety, not proactively rescuing workers after accidents happen".

It also urged appropriate punishment for bosses who order staff to work in risky conditions or pay bribes to avoid regulation.

The chairman and general manager of the Baoyuanfeng poultry plant have been arrested, provincial officials said last week.

When the fire spread after an apparent chemical leak, workers were blocked from escaping because only one of the building doors was open, the Southern Metropolis Daily reported.

Other doors were locked to prevent workers taking toilet breaks, state-run broadcaster CCTV said.

The fire was China's worst since a blaze on December 25, 2000, in a shopping centre at Luoyang in the central province of Henan, left 309 people dead.

Fatal accidents are reported regularly at Chinese mines and factories, with critics blaming lax enforcement of rules.

While laws may allow for strict standards or punishments, the lack of an independent judiciary can mean court decisions become subject to political or other considerations.