Indian security forces killed four alleged fighters in occupied Kashmir on Saturday, police said, as the disputed Muslim-majority territory simmers under a lockdown imposed by New Delhi after it revoked its constitutional autonomy in August.

Three were killed in the Batote market area of Jammu where, according to officials, they had allegedly taken a local civilian hostage inside his house.

The hostage was rescued unharmed, a spokesman for the central reserve police force told journalists.

Another Kashmiri was killed in an 'encounter' in Kangan in the north of the region, Dilbagh Singh, director general of Jammu and Kashmir police told AFP.

Singh also said Kashmiri fighters had thrown a grenade in the Safakadal area of Srinagar city but that no one was injured in the incident.

According to Kashmir Media Service, on the other hand, Indian troops killed three youth during cordon and search operations in Naranag area of Ganderbal and three others in Batote area of Ramban district in the Jammu region.

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Indian security forces had tightened restrictions in Kashmir and the Hindu-majority Jammu region on Friday, fearing protests ahead of speeches at the UN by the leaders of India and Pakistan.

In his address, Prime Minister Imran Khan warned the body that the dispute with India over Kashmir could escalate into an all-out nuclear war that would have consequences for the world.

The India-occupied region has been facing a clampdown since August 5, when the Indian government nixed Article 370 of the Indian constitution, which conferred a special status on it.

Scores of people, including mainstream and separatist leaders, have been detained or arrested by authorities since the Indian government made the move.

Indian Prime Minister Narendra Modi's Hindu-nationalist government has faced criticism and calls to restore communications and ease restrictions in Kashmir.

India has repeatedly insisted that Kashmir is purely an internal matter and has bristled at outside comment or suggestions of mediation.