New Delhi, Jan 14 (IANS): The killing of two Indian soldiers -- one of whom was beheaded -- by Pakistani troops is a "gruesome and an unpardonable act," Army Chief General Bikram Singh said Monday, and asserted that his forces "reserve the right to retaliate".

"What they (Pakistan) have done is against the ethics of soldiering. My heart goes out to the families of soldiers who were killed and whose bodies were mutilated. It's a gruesome and unpardonable act. Beheading of soldiers is not acceptable," Singh told reporters here.

He also said that the Indian Army will uphold the ceasefire as long as it is maintained.

"We will uphold the ceasefire as long as it is maintained. We reserve the right to retaliate at the time and place of our choosing," Singh said.

Appreciating the Indian soldiers, Singh said: "Commanders on LoC are doing a great job. I expect my commanders on the LoC to be aggressive. They must understand that the army hierarchy is behind them."

Border tensions between India and Pakistan have risen sharply since the Jan 6 death of a Pakistani soldier in alleged firing by Indian forces along the Line of Control in Jammu and Kashmir.

Two days later, on Jan 8 Pakistani soldiers killed and mutilated two Indian soldiers in the Mendhar sector in Poonch district of Jammu and Kashmir. The soldiers were identified as Lance Naik Sudhakar Singh and Lance Naik Hemraj of the Rajputana Rifles.