A massive explosion at a fireworks factory in northeast China has risen to at least 19 workers, with five still missing.

Up to 50 people were working at the factory in the city of Yichun in Heilongjiang province when it was rocked by the explosion.

The blast damaged nearby buildings and caused secondary blasts, according to a statement posted on the local government's website.

A total of 153 people were injured by the explosion, which could be felt up to five kilometres away. It smashed windows in the local government offices and other buildings.

Safety is lax at Chinese fireworks plants, and accidents are common. Dozens of people also die each year from unsafe handling of fireworks while celebrating weddings and traditional holidays.

Although deadly accidents persist, China has placed an increasing emphasis on improving industrial safety.

Fatalities in the country's notoriously dangerous coal mines decreased to 2,631 last year, compared with a peak of 6,995 deaths in 2002, according to official figures. That works out to 7.2 deaths a day in 2009, down from 19.1 a day in 2002.