Guwahati, March 24: A bicycle seized from an Assam militant a fortnight ago and dumped in a police station storeroom has turned out to be a two-wheeled bomb containing enough explosives in the hollow of its steel frames to maybe blow up a tank.

The police chief of Kamrup district, Debojit Hazarika, said the bicycle was brought out of the storeroom in Sualkuchi, 32km from Guwahati, and dismantled after the arrested Ulfa militant revealed last night that it was a bomb in itself.

The frames of the bicycle were found to be stuffed with a combination of TNT and pentaerythritol tetranitrate or pentrite, a potent explosive used for the first time by the Germans in World War I.

“Only the detonator was missing,” Hazarika said.

He said all that remained for the militant to do to make the bomb explosion-ready was to lift the seat and fit in the detonator.

The banned Ulfa routinely straps remote-controlled or timed improvised explosive devices to bicycles for blasts in public places, but this is the first known instance of one being converted into an RDX and pentrite-powered bomb.

The militant who was riding the bicycle, Binoy Baishya, was arrested in Sualkuchi — a township famous for its silk — on March 10. The police team that had stopped Binoy at a checkpoint that day found a bomb and some programmable timer devices in the bag he was carrying and arrested him. The bicycle he was riding went straight into the storeroom of the police station and the militant kept mum.

The officer-in-charge of the police station, R.P. Singh, said Baishya was shifted to nearby Rangiya town after a court remanded him in police custody. It was there that he “broke down” and told the sub-divisional police officer, A.P. Tiwari, that the bicycle he was riding at the time of his arrest was actually the “bigger bomb”, Singh said.

Officials of security agencies engaged in counter-insurgency operations said Binoy’s revelation had made their job more difficult. “Militants have been putting bombs even in pressure cookers and empty LPG cylinders, but who would have thought the parts of a bicycle would be used the way he did? Our job has become more difficult. From now on, we will have to check not only the bags hanging from bicycle handles but what is inside the hollow steel bars, too,” a constable at Sualkuchi police station said.

The checkpoint where Binoy was intercepted had been set up after the police received information about an Ulfa militant ferrying a bomb to Bompara, near Sualkuchi. A bomb strapped to a bicycle exploded in the garrison town of Tezpur only last month, killing one person. That was the first explosion in a public place in Tezpur, the headquarters of the 4 Corps army formation that heads counter-insurgency operations.