Skirmishes are frequent across the so-called Line of Control (LoC), but the latest deaths in two separate incidents come after Pakistan warned it was ready to meet any Indian aggression over Kashmir.

"In efforts to divert attention from precarious situation in IOJ&K (Indian-held Kashmir),Indian Army increases firing along LOC. 3 Pakistani soldiers embraced shahadat (martyrdom). Pakistan Army responded effectively," the Pakistani military said in a statement.

It also claimed that "5 Indian soldiers (were) killed, many injured, bunkers damaged. Intermittent exchange of fire continues," without specifying further where the incident took place.

An Indian army spokesman told the Press Trust of India late Thursday that the Pakistan claims were "fictitious", adding that the army was on high alert to deal with any "misadventure" by Pakistan.

Separately, two civilians were killed and one injured by the Indian troops along the LoC in Rawalakot district in Pakistani-held Kashmir, a senior local official there told AFP.

The official, Mirza Arshad Jarral, said intermittent exchanges of fire between the two militaries had been going on since morning.

The former princely state of Kashmir was divided between Pakistan and India on their independence from Britain in 1947.

They have fought two of their three wars over the territory -- though none since both countries acquired nuclear weapons.

Tensions skyrocketed following India's shock move to revoke the autonomy of its portion of the disputed Himalayan territory last week.

On Wednesday, Pakistani Prime Minister Imran Khan addressed the local legislative assembly of the Pakistani-administered Kashmir in Muzaffarabad.

He vowed the time had come to teach Delhi a lesson and promised to "fight until the end" against any Indian aggression.

Khan has likened India's moves in Kashmir to Nazi Germany, accused them of ethnic cleansing, and appealed to the international community to take action.

Islamabad has also expelled the Indian ambassador, halted bilateral trade and suspended cross-border transport services.

However, analysts said the actions were unlikely to move Delhi.

Earlier this year Pakistan and India came close to all-out conflict yet again, after a militant attack in Indian-held Kashmir in February was claimed by a group based in Pakistan, igniting tit-for-tat air strikes.