At least 10 people were killed and several others seriously injured in an explosion at a steel factory in southeast India, a local government official said on Thursday.

"Ten people died in the blast on Wednesday evening and about nine are battling for their lives in hospital," Lav Agarwal, district administrator of Visakhapatnam in the state of Andhra Pradesh, told AFP.

A spokesman for the plant who declined to be named said that first reports suggested that the explosion occurred in a control room, but that the cause of the blast was uncertain.

"We found people with 75 percent burns who were rushed to the hospital," he said. "An oxygen supply pipe burst and we are investigating."

The state-owned Rashtriya Ispat Nigam plant, situated in Visakhapatnam, 600 kilometres (370 miles) from the state capital Hyderabad, was hit by another fatal accident last month when two workers were killed at the furnace site.

Local media reported that a fire broken out on Wednesday after a huge blast heard at about 8:00 pm, and that firefighters continued to battle the blaze in the morning as a full search for any further bodies was undertaken.

Many of the victims, who were all factory employees or contract workers, were treated at a hospital on the plant site with some of the injured moved to public hospitals in the coastal city of Visakhapatnam.

The Hindu newspaper reported on its website that eight people died at the scene and two others had died of their injuries in hospital.

It said that one general manager and three deputy general managers were among the dead.

The plant, which is commonly known by the name of Vizag, was set up in 1971 and has recently raised its annual capacity from 3.0 to 6.3 million tonnes of liquid steel.

As part of the ongoing expansion plan, a new blast furnace was commissioned in April.

The plant's management did not immediately release details about the blast or any casualty numbers.

Lax safety standards are a regular problem in India's factories, and union leaders had raised concerned that the rapid expansion of the Rashtriya Ispat Nigam plant could lead to a dangerous environment for workers.