Though no party or student body has called a shutdown against the bill that will fast-track citizenship claims for immigrants from three neighbouring countries - but not if they are Muslim, protesters fought pitched battles with security forces, including in front of the secretariat, the seat of the BJP government.

While opposition parties have called the law unconstitutional for making religion a criteria for immigration, residents in ethnically-diverse northeastern states like Assam and Tripura have launched protests because it stands to give citizenship to large numbers of Hindus who have emigrated from Bangladesh in recent decades.

fired blank shots, tear gas shells and lathi-charged protesters, a majority of them students, in different parts of Guwahati, Assam biggest city, as several thousand demonstrators attempted to barge past security barriers to converge on the adjoining state capital Dispur. According to student leaders, many protesters were injured in police action in front of the secretariat. Several vehicles were set on fire.

All senior civil and police officials were incommunicado but, according to unofficial accounts, hundreds of protesters have been detained in Guwahati and other places like Dibrugarh and Jorhat, news agency PTI reported. The curfew in Guwahati will be in place till 7 am on Thursday, Assam Police Director General Bhaskar Jyoti Mahanta told News Agency.

large number of students blocked the road near the secretariat complex and pulled down the barricade erected on the arterial G S Road, provoking police action.

They also damaged a stage erected on the road for Prime Minister Narendra Modi's proposed summit meeting with his Japanese counterpart Shinzo Abe on Sunday, PTI reported. Hoardings and banners advertising the government's schemes were pulled down and set afire in front of the secretariat.

Protests were reported in Jorhat, Golaghat, Tinsukia, Sivasagar, Bongaigaon, Nagaon, Sonitpur and many other districts since the morning.

A motorcycle rally was organised against the Citizenship (Amendment) Bill in Chief Minister Sarbananda Sonowal's hometown Chabua.

Gauhati University, Cotton University and Dibrugarh University postponed examinations scheduled for Wednesday. The campuses were deserted with hardly any student around.

The Northeast Frontier Railway was forced to cancel many trains and rescheduled some that originate from the state.