Tehran, Dec 10 (IANS): A huge fire broke out on Sunday morning at an oil refinery in Iran's South Khorasan province, leading to the simultaneous explosion of several gas condensates reservoirs, the media reported.

According to semi-official Tasnim news agency, the fire broke out at one of the reservoirs of the mini-refinery at 8:45 a.m. local time (0515 GMT), Xinhua news agency reported.

When firefighters were trying to contain the blaze at the refinery belonging to the Azaran Sanaat Barsava company, it spread to other nearby reservoirs, causing them to explode simultaneously.

"Five firefighting groups as well as a number of fire engines are at the scene trying to cool the nearby reservoirs down to prevent the further spread of the blaze," Tasnim quoted Birjand's Governor Ali Fazelifard as saying.

The refinery had been completely evacuated to minimise potential human casualties, noting the cause of the incident had not been determined yet.