A fire at a fireworks factory in central India has killed at least 15 people and seriously injured four others, police have said.

The blaze started at a manufacturing plant in Ujjain in Madhya Pradesh state when workers were making firecrackers, police officer Kishore Gurjar told the Associated Press news agency.

The four injured workers were battling for their lives in a hospital, Gurjar said.

Local media reports said the death toll was expected to rise.

Police have said the cause of the fire was not immediately known and was being investigated.

There are fatal accidents nearly every year in India as people work in makeshift factories, often employing children in the absence of proper safety standards.

India has a huge demand for firecrackers, which are used in religious festivals and weddings.

Factories start producing crackers months before the nation's biggest Hindu festival, Diwali, or Festival of Lights, when people set off fireworks in celebration.

Source: Agencies