Srinagar: Three Indian soldiers were killed and two injured in an explosion at a polling booth in Kashmir, where ten more people died in other related separatist violence, officials said.

A device, which officials said was planted by Muslim rebels, exploded in Sogam village in the Lolab area of the Northern Kupwara district overnight.

The three who died were members of the Border Security Force (BSF).

"The condition of one of the injured is serious," a BSF spokesman said.

He said the explosion occurred inside a school building, which was to be used as a voting station on October 8 when Lolab goes to the polls in the last stage of four- phase elections for the state Assembly.

"BSF personnel had just moved in when the explosion took place," the spokesman said, adding militants had previously planted the device inside the building.

"Our boys were sanitising the building when the explosive device went off," he said.

The vote in Lolab was due to take place during the first phase on September 16, but was postponed after the state's law minister, Mushtaq Lone, who was standing as a candidate for the ruling National Conference party was assassinated on September 11.