An explosion at a fireworks factory in central Thailand has killed at least 23 people, officials said.

The cause of the blast in Suphan Buri province is under investigation.

Officials are working to secure the site and help people who were affected.

Rescue workers at the scene said no survivors had been found. None were mentioned by provincial authorities, contradicting an earlier statement by the department of disaster prevention and mitigation that injured people had been recovered.

Suphan Buri is about 60 miles north-west of Bangkok, in the heart of Thailand’s central rice-growing region.

The office of Prime Minister Srettha Thavisin, who is in Switzerland for the World Economic Forum, distributed a video showing him being told over the phone by the regional police commander that there were 20 to 30 workers at the factory at the time of the explosion and that none of them could be found.

Kritsada Manee-In, a rescue worker with the Samerkun Suphan Buri Rescue Foundation, had earlier estimated that around 15 to 17 people had been killed.

Photos posted on social media showed a thick plume of black smoke rising over the scene of the blast in an otherwise unoccupied rice field.

Photos posted online by local rescue workers showed the factory site virtually levelled flat, with debris and body parts also visible.

National police chief Torsak Sukvimol confirmed local news reports that there had been another explosion at the factory in November 2022 that killed one worker and seriously injured three others.

He said police would pursue legal action for any wrongdoing involved.

The blast, the cause of which was not immediately clear, came less than a month before Chinese New Year in February, when demand for fireworks is strong.

In July last year, a large explosion at a fireworks warehouse in southern Thailand killed at least 10 people and wounded more than 100, according to officials.

That explosion in Narathiwat province was in a residential area and damaged about 100 houses within a 1,640ft radius.

The Narathiwat governor said that blast was likely ignited by construction work in the warehouse, with sparks from metal welding causing the fireworks stored inside to catch fire and explode.