Fourteen people were injured, three critically, when two grenades exploded inside a cinema hall in Assam's Dhubri district on Saturday as the United Liberation Front of Asom struck on the eve of the Independence Day.

Police sources said that two grenades exploded in the 'third class' section of Urobi cinema hall at Gauripur town during the noon show screening of Bengali film, 'Mayer Anchal'.

There were 62 people in the theatre and all the injured were male. The wounded were admitted to the Dhubri Civil Hospital where the condition of three was stated to be critical and they were likely to be shifted to Guwahati after their condition stabilised, the sources said.

The police cordoned off the cinema hall and security in the entire town has been beefed up with a massive combing operation launched to nab the culprits, the sources said.

The ULFA had last year issued a ban against screening of Hindi films in the cinema halls of the state and had carried out a series of attacks in theatres across Upper Assam towns. But today's attack was the first in Lower Assam.

In the run-up to the Independence Day, the banned outfit also blew up a crude oil pipeline near the Shalmari Oil Collecting Station (OCS) of Oil India Limited near Tingkhong in Dibrugarh district late last night.
 
Six underground outfits of the Northeast, including the ULFA, KLO and NDFB, have called for "boycott" and "general strike" during the Independence Day celebration.

ULFA militants had struck last week in Guwahati when they hurled grenades at a BSF vehicle and had also exploded IEDs in power transmission towers of Powergrid Corporation of India Limited and Assam State Electricity Board (ASEB) in Jorhat.