May 20: Silent for some time, the guns of the banned Ulfa boomed again today to kill a soldier and injure four in the Upper Assam district of Sivasagar.

The ambush on a convoy of the Indo-Tibetan Border Police followed twin blasts on the rail track between Gossaigaon and Fakiragram stations in Kokrajhar district last night. Two railway employees were injured in the second blast, which occurred nearly two hours after the first. Train services on the route were suspended for the night.

At least three passenger trains, including the Guwahati-bound Kanchenjunga Express and the Avadh-Assam Express, were to cross the site of the blasts after midnight.

The Ulfa ambush occurred at Borhat, near the Dili forest reserve on the Namrup-Sonari road, around 10.30 am. The site is about 8 km from the Arunachal Pradesh-Assam border.

A senior police official said a Swaraj Mazda carrying a nine-member Indo-Tibetan Border Police team was on its way from Changlang in Arunachal Pradesh to Kanubari in Sivasagar district when the militants, who lay in wait atop the hills flanking the road, opened fire from sophisticated weapons.

Caught unawares, the security personnel could not retaliate immediately. By the time they did, the militants had fled towards the forests of Arunachal Pradesh.

The only casualty in the attack, Pradip Kumar, succumbed to injuries in hospital. The other four injured jawans ? Deo Prakash, Karan Chand, Admi Singh and Hitendra Kumar ? were in a critical condition till late tonight. They were admitted to the Assam Medical College and Hospital in Dibrugarh.

The Indo-Tibetan Border Police team was led by assistant commandant Dinesh Kumar.

Sivasagar superintendent of police Dipak Kedia said the police launched an operation in the area soon after the ambush.

Several rounds of empty cartridges were found at the site.

The ambush virtually shot down the Congress government?s claim that the Ulfa was a spent force and capable of only triggering blasts from a safe distance.

The incident also gave the government, which is desperate to bring the Ulfa leadership to the negotiation table, something more to worry about.

In another development, the arrested mastermind of the blast in Dhemaji on August 15 last year revealed to interrogators that Ulfa commander-in-chief Paresh Barua had personally instructed the outfit?s crack unit to disrupt the Independence Day celebrations.

Dhemaji additional superintendent of police (headquarters) Swapnanil Deka quoted Rashid Bharali, a ?lance corporal? in the Ulfa hierarchy, as saying that Barua had instructed the operations commander of the outfit?s 28 Battalion, Mrinal Hazarika, to make arrangements to trigger blasts at the parade grounds.

Hazarika, in turn, asked Jiten Dutta, the deputy operations commander of the 28 Battalion, to find ?someone reliable? to carry out the operation and Rashid was chosen for the job, the police official said.

Bharali was arrested on May 11 at Handique village, under Simen Chapori police outpost of Dhemaji district. Clues provided by him led to the arrest of Md Hasifuddin, the suspected ISI agent who supplied explosives to Ulfa for the Dhemaji blast.

Meghalaya police caught him on Sunday evening with over 400 gelatine sticks, enough to blow up a large housing complex.