The bill was approved Monday in the lower house, where Prime Minister Narendra Modi's Hindu nationalist government enjoys majority support. The bill still needs the backing of smaller regional political groups in the upper house for it to become law.
The Press Trust of India news agency reported that police fired rubber bullets and used batons and tear gas to disperse protesters in Dibrugarh district in Assam state on Wednesday. Streets protests were also reported in Gauhati, the state capital.
The protesters organized an 11-hour shutdown on Tuesday to voice opposition to the bill out of concern that more migrants who come to the country illegally will move to the border region and dilute the culture and political sway of indigenous tribal people.
Introducing the bill in the upper house, Home Minister Amit Shah said the bill was not anti-Muslim as it did not affect the existing path to citizenship available to all communities. It seeks to address the difficulties of Hindus and other minorities who suffered persecution in Muslim-majority Pakistan, Bangladesh and Afghanistan, he said.
Anand Sharma, a leader of the main opposition Congress party, said the bill was discriminatory because India's constitution provides equal opportunities to all communities. Some opposition members complained that the the bill excluded Tamil Hindus who fled Sri Lanka during that country's civil war.
Meanwhile, the U.S. Commission on International Religious Freedom criticized the bill as going against "India's rich history of secular pluralism," and called for American sanctions against Home Minister Shah if the bill is passed by both houses of Parliament.
External Affairs Ministry spokesman Raveesh Kumar said the U.S. commission's criticism "is neither accurate nor warranted.''
"The bill provides expedited consideration for Indian citizenship to persecuted religious minorities already in India from certain contiguous countries. It seeks to address their current difficulties and meet their basic human rights," Kumar said in a statement. "Such an initiative should be welcomed, not criticized by those who are genuinely committed to religious freedom.''