Militants of the banned ULFA continued their violent activities in the run-up to Independence Day, injuring nine policemen, two of them critically, in a grenade attack in upper Assam's Tinsukia district, police said.
A group of militants lobbed a powerful grenade on Panitola police station about eight km from Wednesday night, the police said.
At least 45 people, including several securitymen, have been injured and one person killed in violence by ULFA since August 4.
Security has been tightened throughout the state in view of the ULFA threat to disrupt the I-day celebration.
The outfit has given a boycott call and road blockade on Independence Day.