The armies of India and Pakistan Sunday exchanged heavy fire and artillery shells once again on line-of-control (LoC) in Indian- controlled Kashmir, officials said.

The ceasefire violation took place Sunday evening along the LoC in Krishna Ghati sector of frontier Poonch district, around 180 km southwest of Srinagar city, the summer capital of Indian-controlled Kashmir.

"Pakistani troops this evening again resorted to unprovoked firing using machine guns and mortars on our several posts," said Col. R K Palta, Indian army spokesman based in Jammu. "We also retaliated back."

LoC is a de facto border that divides Kashmir into Indian and Pakistani controlled parts. "We have not suffered any damage due to Pakistani firing today," said Palta.

The ongoing skirmish since last Sunday between Indian and Pakistani troopers on LoC is heightening tension between the two nuclear neighbors. So far four troopers of both countries, two from each side, were killed in these skirmishes on LoC.

Both New Delhi and Islamabad accuse each other of resorting to unprovoked firing on LoC and breaching the ceasefire line. New Delhi and Islamabad in 2003 agreed to observe a ceasefire along the international border and LoC in Kashmir. Though some violations have been reported on both sides, the ceasefire remains in effect.

Kashmir, the Himalayan region divided between India and Pakistan, is claimed by both in full. Since their independence from British, the two countries have fought three wars, two exclusively over Kashmir.

Pakistan said it wants a third party inquiry into the ceasefire violations on the LoC. Islamabad, according to reports, has already contacted United Nations Military Observer Group in Indian and Pakistan (UNMOGIP) and proposed investigation into ceasefire violations. However, New Delhi has rejected any UN investigation, saying they do not want to internationalize the issue.

An office of UNMOGIP is also in Srinagar. The office was set up in 1949 to monitor the ceasefire line, now known as LoC.