Guwahati: Suspected ULFA rebels on Monday triggered a blast at the state Congress headquarters here, injuring at least five party members.

The Central government has already issued a warning about possible violence by the ULFA to disrupt assembly polls in Assam.

The explosion seriously injured spokesmen Mehdi Alam Bora and Akhya Rajkhowa while general secretary Ranjan Bora and two others received minor injuries.

The injured have been admitted to the Gauhati Medical College hospital.

The ULFA's anti-talk faction, led by 'commander-in- chief' Paresh Baruah claimed responsibility for the attack.

Chief Minister Tarun Gogoi had earlier said that the anti-talk faction had issued threats to Congress candidates ahead of the Assembly election slated for next month.

The Home Ministry last week had also conveyed to the Assam government that the anti-talk faction may try to attack Congress workers ahead of the two-phased assembly elections on April 4 and 11.

The Centre has deployed 100 paramilitary companies in the state for the two-phase polls slated for April 4 and 11.

According to police, the militants detonated an improvised explosive device (IED) around 6.50 pm at Rajiv Bhavan in Tarun Nagar area where some party members gathered to welcome APCC president Bhubaneswar Kalita.

DGP Shankar Baruah said a detonator of the IED was retrieved from a garbage dump near the APCC headquarters.

DGP Baruah said police were aware of threats issued by insurgent groups to candidates in the run-up to the election. The city has been thrown under a strict security blanket and a
search operation is on in various parts.

Violent incidents had shown a downward trend in Assam in the past few months following the surrender of several top leaders of the banned ULFA and their holding of talks with the
Centre. ULFA military chief Paresh Baruah is, however, opposed to the talks and has pledged to carrying forward the group's arm struggle.

The ULFA observes March 16 as its 'raising day' as the group's armed wing was formed that day in 1979. 

Assam government spokesman and Health Minister Himanta Biswa Sarma said these incidents will only help in regrouping "our partymen to provide a united fight to the divisive

Meanwhile Chief Minister Gogoi visited the Gauhati Medical College Hospital where the two seriously injured party spokesmen were being treated. Doctors said both are out of danger.

On the other hand, Opposition AGP said its candidates have not received any threats from insurgent groups so far.

"There is absolutely no threat issued from any quarter to our candidates. There is no such complaint," party president Chandra Mohan Patowary said.

He also denied the charge of ruling Congress that it has links with the banned ULFA and so has not received any threat.