More than 30 people have been punished over a power plant blast that killed 22 people in central China last year and 14 more are awaiting trial, the official Xinhua news agency reported on Friday.

The power plant blast in Dangyang city in central Hubei in August 2016 occurred on the eve of the first anniversary marking massive Tianjin explosions that spurred government efforts to improve industrial safety.

Xinhua said 30 people had been punished over the blast, but gave no details, and that Yu Huaqiang, general manager of Huaqiang Chemical Group, which built the power plant, and 13 others were currently awaiting trial or under investigation.

Citing the Hubei Provincial Work Safety Bureau, which led an investigation into the incident, Xinhua said workers were testing thermo power facilities when the accident happened and the blast was caused by a leak from a poor quality pipe nozzle.

The factory's design did not meet safety standards and the control room was not sufficiently reinforced to protect people inside, it said, adding that workers did not follow standard procedures when testing the pipes.

Deadly accidents are relatively common at industrial plants in China, and anger over lax standards is growing after three decades of swift economic growth marred by incidents from mining disasters to factory fires.

China has vowed to improve safety at such facilities. President Xi Jinping has said authorities would learn the lessons paid for with blood after chemical blasts in the port city of Tianjin in 2015 killed more than 170 people.