Pakistan's military has accused the Indian army of killing one of its soldiers with "unprovoked firing" in the disputed territory of Kashmir.
A military statement said the "ceasefire violation" occurred along the Line of Control (LoC) in Hot Spring and Jandrot sectors.
India has denied the allegation.
Tensions have risen following deadly exchanges along the border last week, in which two Indian soldiers and two Pakistani soldiers died.
The violence has plunged the neighbours into the worst crisis in relations since the Mumbai attacks of 2008, which were blamed on militants based in Pakistan. Both sides deny provoking last week's clashes.
The Pakistani army's director of military operations will call his Indian counterpart and "protest strongly" about the latest incident, a statement issued by the army said.
Pakistan said a soldier, identified as Naik Ashraf, was killed in "unprovoked" firing by Indian troops on Tuesday night.
Indian army spokesman Col RK Palta told the Associated Press news agency that Pakistani troops had fired at Indian soldiers using small arms and mortars in the Poonch area.
"Our troops didn't fire at all," he said.
Earlier on Tuesday, Indian PM Manmohan Singh said the killings of the Indian soldiers last week - one of whom India says was beheaded - was "unacceptable".
"After this barbaric act, there cannot be business as usual with Pakistan," he said. "I hope Pakistan realises this. I hope Pakistan will bring the perpetrators to book."
Pakistan Foreign Minister Hina Rabbani Khar said India was "war-mongering" and this was "detrimental to the peace process between the two countries".
"It is deeply disturbing to hear statements which are upping the ante, where one politician is competing with the other to give a more hostile statement," Ms Khar was quoted as saying in New York by the AFP news agency.
On Monday Indian army chief Gen Bikram Singh accused Pakistan of "pre-meditated, pre-planned activity", and urged Indian troops to be "aggressive and offensive in the face of provocation and fire" from Pakistan.
But despite Indian accusations that Pakistan is in breach of ceasefire accords, two Indian newspapers have suggested the reverse may be true.
The reports last week said Indian commanders might have precipitated the clashes by ordering new observation posts on the LoC.
The Indian army has denied any provocative actions but said there had been "routine maintenance of fortifications".
India was set to begin a landmark visa-on-arrival deal for Pakistani senior citizens at the Wagah crossing, but this has been put on hold. It has also ordered Pakistani hockey players to return home from India.
Both countries have also summoned each other's envoys to protest about the killings of the soldiers.
Officials held a meeting at the border on Monday aimed at reducing tensions. Neither side have commented on the talks.
Claimed by both countries, Kashmir has been a flashpoint for over 60 years and two wars have been fought over it. Exchanges of fire in the disputed area are not uncommon but rarely result in fatalities.