Guwahati: With the Union Home Ministry alerting the Assam government to tighten security ahead of ULFA's 'army day' on Friday, DGP Jayanta Narayan Choudhury on Thursday said that three districts in the state were an area of concern.

"Three districts in upper Assam are an area of concern and we are on maximum alert," Choudhury who recently took charge told media here referring to Tinsukia, Dibrugarh and
Sibsagar districts where the outfit has influence.

The DGP also identified as vulnerable two lower Assam districts of Goalpara and Dhubri besides Guwahati and said extreme care would be taken.

He said several youths had been picked up and police pickets posted in vulnerable districts.

The outfit observes 'army day' on the raising of its armed wing in 1979 under 'commander-in-chief' Paresh Barua who now heads the anti-talk faction.

Asked to comment on the recent grenade attack at Zoo Road in the heart of the city on February 28, the DGP said it was attempt by the ULFA to make its presence felt.

"We are also expecting that such attempts will be made but the security forces are ready," he said.

He said that the police had inputs about ULFA's plans to step up extortion drives and subversive activities.

"While the extortion drive is expected to go up, the positive thing is that people are not willing to pay up and are prepared to counter the threat. We want to ensure that the positive trend continues," he said.

The DGP denied the hand of any militant outfit in the kidnapping of a doctor, M C Agarwal, from the city on March 13 and said it was the work of criminals.

Stating that the doctor's car was found last night near the Assam-Bhutan border, he said that the police were trying to trace him.