Four policemen were killed Saturday in a bomb blast set off by suspected Islamist militants in Indian Kashmir, police and reports said, marking a deadly start to the new year in the restive valley.

They were on patrol when the improvised explosive device (IED) exploded in Sopore, some 50 kilometres (30 miles) from the main city of Srinagar.

"IED blast in Sopore. Four policemen martyred," Jammu and Kashmir police said on Twitter.

The bomb was planted by militants near a shop amid a strike called by separatists, the Press Trust of India and other local media said.

The latest incident comes during a spike in violence in the disputed region which is claimed in full by India and Pakistan.

Last week four Indian soldiers were killed in an attack by armed militants who stormed a paramilitary camp outside Srinagar.

Kashmir was divided between India and Pakistan at the end of British colonial rule over the subcontinent in 1947.

Since 1989, rebel groups have been fighting roughly half a million Indian soldiers deployed in the territory, seeking independence for the former Himalayan kingdom or its merger with neighbouring Pakistan.

The fighting has left tens of thousands, mostly civilians, dead.

Last year 206 suspected militants, 57 civilians and 78 Indian security forces personnel were killed, making it the deadliest year in a decade.

New Delhi accuses Pakistan of sending militants across the disputed border in Kashmir to launch attacks on Indian forces.

Islamabad denies the allegations, saying it only provides moral and diplomatic support to the Kashmiri struggle for the right to self-determination.