Media playback is unsupported on your device Media caption It took firefighters hours to bring the blaze at the plant under control

The death toll in a huge blast at a chemical plant in eastern China has jumped to 47, with 90 badly injured, according to state news agency Xinhua. 

Many neighbouring factories inside the industrial park caught fire after the explosion. 

China's earthquake administration reported a tremor equivalent to 2.2-magnitude at the time of the blast. 

The death toll makes it one of the country's worst industrial accidents in recent years. 

The blast happened at about 14:50 local time (06:50 GMT) on Thursday at a plant in Yancheng, run by Tianjiayi Chemical. 

According to Xinhua, a total of 640 people were sent to hospital.  Many were in critical condition and dozens had severe injuries, the agency reports. 

Image copyright Reuters Image caption The scale of the destruction is clear

Image copyright Getty Images Image caption Hundreds were injured in the explosion, which was reportedly started by a fire at the plant

Images of the site showed a fireball exploding, billowing clouds enveloping the area, injured people, and damage to buildings. 

The blast was so powerful that it knocked down factory buildings some distance away, trapping workers, according to local media. 

Staff at the Henglida Chemical Factory, 3km (1.8 miles) from the explosion, said its roof collapsed as they fled, and windows and doors were blown out. 

Provincial authorities said firefighters had to be brought in from across the province. 

The fire was brought under control at around 03:00 local time on Friday, state TV said. 

Image copyright Getty Images Image caption The cause of the accident is under investigation

One woman, who gave her surname as Xiang, said she had been concerned about safety and pollution levels at the plant for some time. 

"We knew we'd be blown up one day," said told AFP. 

Reuters quoted local officials as saying there had been no abnormalities detected at the site before the blast, but that the province would be conducting emergency inspections of other chemical producers and warehouses. 

Image copyright Reuters Image caption The blast blew out windows of buildings across a wide area

Industrial accidents ranging from factory fires to mining disasters are common in China, often due to poorly enforced safety standards. 

The biggest accident in recent years was the August 2015 Tianjin explosion, which killed more than 160 people and injured nearly 1,000. 

The exact cause of Thursday's explosion is still under investigation.  Tianjiayi Chemical, founded in 2007, has received six government penalties in the past over waste management and air pollution, according to the South China Morning Post. 

President Xi Jinping has called for an "all-out effort" to aid the injured and said authorities must learn lessons from the blast prevent future accidents.