Three people were killed when a DIY fertiliser factory exploded in Thailand on Tuesday.

The workers had been mixing chemicals to create a flowering agent for the longan trees in their boss's orchard in Chiang Mai province.

However, the precursors reportedly ignited, with the blast tearing through the one-storey factory on November 28.

Police Colonel Phongthasat Charoenpreechayapong, superintendent of the Phrao Police Station, said cops received a report at 3:30 pm. They went to investigate the scene and found the building obliterated with only its frame left standing.

Two women were reportedly torn to shreds by the blast. They were identified as Burmese worker Daeng, who was buried in the wreckage, and Thai woman Natchaya Sunanta, who was flung onto a tree in the longan orchard.

A Burmese man Aung, 34, suffered serious burns and was rushed to the hospital. However, he later died to his injuries.

The unnamed orchard owner said the workers had been mixing sacks of potassium chlorate - a substance also used in making fireworks and explosives - with urea when the explosion occurred.

Police Colonel Phongthasat said: 'It is believed that the accident was caused by the ignorance of the newly hired workers. There was a mixture of chemicals that caused a flammable reaction.'

He said the orchard owner will face three charges: unauthorised possession of dangerous chemicals, committing acts that cause serious injury or death to others, and providing shelter and employment to foreign workers without permission.

Authorities said potassium chlorate was commonly used by longan farmers to stimulate growth.

A similar explosion involving the chemical was reported to have occured in the San Pa Tong district of Chiang Mai in 1999.