Indian troops shot dead a Pakistani soldier along the de facto border in the disputed Kashmir region in the first deadly exchange since a truce was agreed a month ago, officials said Friday.

An Indian army spokesman said that the soldier had been killed in a firefight in which one Indian soldier was also wounded, and an AK47 rifle was discovered by his side when the body was recovered.

"We detected some suspicious movement yesterday near the LoC (Line of Control) inside our territory and the challengers from our side fired and in the ensuing firefight he was killed," Lieutenant Colonel Rajesh Kalia, a spokesman for the Indian army's northern command, told AFP.

"At that time we did not know he was a Pakistani soldier. We killed an infiltrator," the spokesman added.

Kalia said that India expected to return the body to the Pakistani authorities later in the day.

The Pakistani military condemned the killing, saying the soldier had become lost and crossed the LoC "inadvertently" and that civilians at the scene had seen him being questioned by the Indians.

"We condemn such an inhuman and brutal act of killing our soldier after he had identified himself and explained his position," a spokesman said.

"This is not the first such event. We have returned Indian soldiers in the past, who had similarly strayed."

The spokesman said the Indians had agreed to return the soldier's body.

Later, Pakistan's foreign ministry demanded an investigation into the incident.

"Pakistan calls upon the Government of India to carry out a thorough investigation into this unfortunate incident and to ensure that such incidents do not recur," the foreign ministry said in a statement.

It was the first fatal exchange between troops in the region since the two armies agreed a ceasefire on January 16.

A flare-up along the LoC in early January saw a total of five soldiers killed, three from Pakistan and two from India.

The Indian government expressed outrage after one of its soldiers was beheaded although the Pakistani army denied responsibility for the decapitation.

Cross-border trade and transport links were also suspended for several weeks although they have since resumed.

Nuclear-armed India and Pakistan have fought two of their three wars over Kashmir. Each administers part of the territory but claims the whole of Kashmir.