Jorhat, March 30: Ulfa militants lobbed a grenade at Mathurapur police station in Sivasagar district last night, just three days after having carried out a similar attack on Demow police station in the district. The grenade, however, did not explode.

Police denied any such incident but sources said the unexploded Chinese grenade was found on the premises of the police station, on Simaluguri-Sonari Road under Charaideo subdivision, this morning.

“The grenade was probably lobbed at the police station late last night,” a source said.

A high alert has been sounded in Upper Assam following the two incidents with intelligence reports saying more such attempts could be made by Ulfa in the run-up to the outfit’s raising day on April 7. Ulfa was formed on this day in 1979 at Rongghar in Sivasagar district.

Ulfa chairman Arabinda Rajkhowa, who leads the pro-talks faction, has also warned of disruptive activities by Ulfa hardliners ahead of the outfit’s raising day. He told reporters in Guwahati yesterday that there was a strong possibility of such attacks by the anti-talks faction.

A police official involved in counter-insurgency operations in Upper Assam said the attacks on the two police stations were made by Nagaland-based Ulfa cadres. “These newly recruited cadres cross the boundary carry out sabotage activities and return to Nagaland.”

He said it had become difficult for security forces to keep track of these cadres because since they were newly recruited, it was difficult to identify them. “Many youths, mostly from the Moran and Motok communities have joined Ulfa in recent times,” he added.

He said Ulfa has been serving demand notes to businessmen, oil companies and tea garden owners in Upper Assam districts. “The outfit wants to show its strength by carrying out attacks, which would create a fear psychosis among the business community and force them to pay up.”

An Austrian oil company closed down its operations in the Bordumsa area along the Assam-Arunachal Pradesh border in Tinsukia district recently following a demand of Rs 70 lakh by Ulfa. Although the police and the army assured full security, the company decided to close down operations after negotiations to lower the amount failed and the March 22 deadline for payment expired.

Deputy inspector-general of police (eastern range) Anurag Tankha has been holding a series of meetings with businessmen and oil and tea companies in Upper Assam, requesting them not to heed to the Ulfa demand and inform the police if and when they received extortion demands from the outfit.