Chinese media and Internet users voiced outrage after officials said the relatives of those killed in a chemical plant explosion were "calm" as they revealed a sharp rise in the toll.

State media said last week that five people had been killed when a fireball ripped through a chemical plant in Shandong province, just weeks after explosions in the northern port of Tianjin killed 161.

Officials in Shandong's Dongying city at the weekend said 13 had died, giving no explanation for the delay, but adding that "the relatives of the victims are all calm now".

Death tolls from accidents are often the subject of suspicion in China, where officials have in the recent past sought to cover up the full extent of disasters.

China's state news agency Xinhua on Monday weighed in by calling the government statement -- which was later deleted -- "cold blooded".

"How could the relatives calm down when they knew that their relatives had been blasted into pieces?" Xinhua said. "Please speak like human beings, officials!"

Internet users also expressed outrage.

"Officials only thought about stability. Even though these people's relatives died, the government thought: they are not making a fuss, so they must be calm," novelist Xia Hanzi wrote on social networking site Sina Weibo.

Some online commenters speculated that the toll announcement had been delayed so as not to coincide with a huge military parade in Beijing last week.

At least 161 people were killed in giant explosions at a hazardous goods storage firm in Tianjin last month, the country's highest-profile industrial accident in years.

The blasts raised questions over corruption and fears about dangerous chemical facilities built close to residential areas, often in violation of guidelines.

State media said that close ties between business owners and government officials had enabled the Tianjin plant to illegally obtain safety permits.

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