Jorhat/Guwahati, April 7: A major fire broke out in the hydrocracker unit of the Numaligarh Refinery Limited in Golaghat district this evening.

It was the first major fire in the history of the refinery, which had, till now, boasted of an impeccable safety record.

The anti-talks group of Ulfa promptly claimed its hand in the fire, but Dispur was equally prompt in ruling out any kind of sabotage, as of now.

The refinery, set up under the 1985 Assam Accord, has seven major units.

The hydrocracker unit is a secondary unit, which cracks heavier hydrocarbons into lighter ones.

NRL corporate communications manager Madhuchanda Adhikary Choudhury told The Telegraph, "The fire was extinguished after one-and-a-half hour and there was no casualty. It occurred at 6.40pm and was noticed within two minutes, as sirens went off."

"We had pressed our own machinery into action. Four fire tenders and one foam tender was pressed into service. It is too early to say anything on the cause of the fire. The fire department has classified it as a major fire," the official added.

A source said the refinery would order an internal inquiry to ascertain the cause of the fire.

Local residents at Numaligarh, 250 km from Guwahati, said there was massive explosion before the fire started.

The refinery had also intimated Digboi and Guwahati refineries to stand by to extend help if the situation so warranted.

The hydrocracker unit, which runs on technology provided by Chevron, a US-based company, was recently revamped during commissioning of the diesel quality upgrade project. The unit was commissioned in 2000.

On January 10, a similar fire broke out in the Guwahati Refinery of Indian Oil Corporation, following an explosion in a tank of hydrocarbon waste of the refinery. The district administration had set up a three-member committee to probe the cause of the explosion after the anti-talks Ulfa group claimed that it had carried out an attack in the refinery.

The inquiry report, however, is yet to be made public.

Significantly, today's incident coincides with Ulfa's raising day. In an email, the Paresh Barua group of Ulfa claimed responsibility for the fire and said it had carried out the attack at the oil installation as part of its "protest programme" announced earlier.

Member of the group's publicity wing, Joy Asom, claimed that it had used a magnetic timer device to carry out the attack.

The group had also claimed responsibility for fires at the refineries at Duliajan and Noonmati.

Assam home commissioner Jishnu Barua told The Telegraph today that the fire was caused by explosion of leaking hydrocarbons. There is no casualty and the fire was under control. When asked about Ulfa's claim, Baruah said so far, there was no evidence of any sabotage.

Security forces as well as NRL authorities have not confirmed whether it was sabotage or a technical snag. "There is no possibility of a bomb being planted at the unit, but we cannot rule out a rocket attack," an NRL official said.

The outfit had threatened to carry out sabotage activities in the run-up to its raising day. The ministry of home affairs had even issued an alert to thwart any attempt by the anti-talks Ulfa group to create disturbance in the run up to the day.

The NRL official, however, said a technical snag was noticed yesterday at the unit, located in the heart of the refinery.

There has been, however, no official word on the extent of damage or how long the unit will be out of order or whether production will be affected because of the fire.

Sources, however, said assessment would be carried out tomorrow.

Copyright 2012 The Telegraph (India), distributed by Contify.com. All Rights Reserved.

(Originally published April 7, 2012, in The Telegraph.)