Suspected militants fired a rifle grenade at a prominent government building in the heart of India's Jammu and Kashmir state capital Srinagar on Saturday and followed it up with two more grenade attacks, officials said.

Two personnel of the Central Reserve Police Force (CRPF) were injured in the attack aimed at the Civil Secretariat, seat of the Jammu and Kashmir state government, CRPF spokesman P Tripathy said.

The grenade aimed at the government building landed near a cinema hall in the locality, he said.

The two other grenade attacks took place near Lalbazar and Hawal in the old quarters of the city, police said. No one was injured in these attacks.

The area around the Civil Secretariat building is a high-security area, but the militants escaped. There were not many people around as Saturday is a holiday.

Islamic militants have stepped up their activity in India-administered Kashmir in the past couple of weeks.

Suspected militants ambushed a group of Indian road workers on Friday in Kishtwar sector, about 265 kilometres north-east of the winter capital Jammu, killing five, including three soldiers of the Indian army who were providing protection for the group, the police said.

The group was ambushed by the militants in a manner similar to that used by the Taliban in Afghanistan, the Indian Express newspaper reported citing army sources.

The Lashkar-e-Toiba, a Pakistan-based militant group has claimed responsibility for the attacks, NDTV television channel reported.

Another dozen people were also injured in a grenade attack on Friday in Baramullah town, about 55 kilometres north of Srinagar. The militants were said to be targeting an army vehicle.

More than 60,000 people have died in the disputed Kashmir region since a violent secessionist militant movement began in the 1980s.

India, which has fought two wars with neighbouring Pakistan over Kashmir, claims the latter aids and abets Kashmiri militants. Pakistan denies the charge and calls Kashmiri militants freedom fighters.

The latest spate of violence in Kashmir comes after a long spell of relative calm.

India and Pakistan are currently engaged in a peace dialogue to resolve differences, including those over Kashmir. (dpa)