India has banned the largest political and religious group in Indian-controlled Kashmir in an ongoing crackdown on activists seeking the end of Indian rule in the disputed region.
The move comes amid the most serious confrontation between India and Pakistan in two decades.
Authorities imposed a security lockdown in several parts of the region on Friday, including in central areas of the main city of Srinagar, in anticipation of protests against Indian rule.
Police and soldiers, carrying automatic rifles and wearing riot gear, erected iron barricades and laid razor wire on roads and intersections to cut off neighbourhoods.
They patrolled streets in Srinagar and imposed restrictions around the city's main mosque, Jamia Masjid, prohibiting congregational Friday prayers there.
India's home ministry issued the five-year ban on Jama'at-e-Islami, or JeI, on Thursday night, accusing the group of being an "unlawful association" and supporting militancy in the region.
Police have arrested at least 400 activists and leaders, mainly from Jama'at-e-Islami, which seeks self-determination for the entire Himalayan region, which is divided between India and Pakistan but claimed by both in its entirety.
Meanwhile, two rebels, a paramilitary officer and a counterinsurgency officer were killed in a gun battle Friday in the northwestern Handwara area, police said.
Five soldiers were also wounded in the fighting.
The crackdown comes amid high tensions between India and Pakistan following the February 14 suicide car bombing of a paramilitary convoy by a Kashmiri militant.
Forty Indian soldiers died in the attack, the worst against Indian government forces in Kashmir's history.
Tensions deepened after Indian aircraft crossed into Pakistan on Tuesday, with Indian authorities claiming to have bombed a militant training centre.
Pakistan retaliated the next day, shooting down two Indian aircraft and capturing a pilot.
"If the unlawful activities of JeI are not curbed and controlled immediately, it is likely to escalate its subversive activities ... by destabilising the government established by law," India's home ministry said in a statement.
The group's head, Abdul Hamid Fayaz, dozens of its top leaders, and at least 300 members have been arrested since last week.
Some of the arrests took place Thursday night in raids by police after the ban, officials said.
The Joint Resistance Leadership, or JRL, which comprises three top Kashmiri leaders, condemned the ban as a "dictatorial measure".
"The dictatorial and repressive measures against Kashmiris have become the order of the day in New Delhi's doctrine of force against Kashmiris", it said in a statement.
India is "punishing people for demanding the resolution of the Kashmir dispute".
Rebels have been fighting since 1989 against Indian control in Kashmir.