No casualty was reported in the explosion.
The office was attacked before Tuesday's proposed North East bandh called by the North East Students Organisation, an umbrella organisation of students' bodies of the region, in protest against the prime minister's announcement to pass the Citizenship Bill.
The office does not have CCTVs installed and hence it is up to the police to identity the assailants, he said.
Protests were on in various places of the region over the Citizenship (amendment) Bill.
The Bill was introduced in the Lok Sabha to amend the Citizenship Act, 1955. It seeks to grant citizenship to people from minority communities - Hindus, Sikhs, Buddhists, Jains, Parsis and Christians from Afghanistan, Pakistan and Bangladesh after six years of residence in India instead of 12 even if they do not possess any proper document.
The Bill has been opposed by a large section of people and organisations in the Northeast.
"The state unit of the BJP has strongly condemned the act of arson in its state headquarters at Bivar Road," BJP Minister A L Hek said in a statement.
An FIR was lodged and copies of it were also sent to the Chief Minister and Home Minister requesting stern action against those involved in the crime, he said.
Hek, who is also the BJP legislature party leader, said the party has also requested the police to deploy security personnel in all its offices across the state to prevent such incident to take place.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)