Four Pakistani soldiers were killed in a mortar attack by Indian forces along the Line of Control in the disputed Kashmir region as tensions between the nuclear-armed neighbours continue to rise.

The Pakistani troops were conducting maintenance on communication lines in the border village of Kotli when they came under attack on Monday, the military said.

After the mortar round exploded, Pakistani forces responded and killed three Indian soldiers while wounding several others, it said.

Four soldiers of #Pakistan Army have embraced martyrdom in unprovoked #Indian firing along the Line of Control in Jandrot-Kotli Sector.

The troops were busy in line communication maintenance when they were fired upon and hit by heavy mortar round by Indian forces. pic.twitter.com/wHLtFdr4nR — Govt of Pakistan (@pid_gov) January 15, 2018

An Indian military official, however, blamed Pakistani soldiers for initially attacking Indian positions and claimed their counter-offensive killed seven Pakistani soldiers.

The officer, speaking on condition of anonymity in keeping with military rules, said Indian soldiers did not suffer any casualties.

At another area along the de facto border, India said its forces killed five fighters from a pro-Pakistan group trying to slip into Indian-administered Kashmir on Monday.

"We allowed them to cross the river and challenged them. All of the five who crossed the river were killed," said Major-General Gulab Singh Rawat.

India's army chief, General Bipin Rawat, accused Pakistan's military of helping fighters enter India-controlled Kashmir.

"Pakistan Army has been continuously trying to help terrorists sneak into India," Rawat said. "If we are forced then we may resort to other action by stepping up [a] military offensive."

On Friday, Rawat said his forces were willing to carry out operations inside Pakistan despite the risks.

"If we will have to really confront the Pakistanis, and a task is given to us, we are not going to say we cannot cross the border because they have nuclear weapons. We will have to call their nuclear bluff," Rawat told a press briefing.

The comments drew derision from Pakistan's foreign minister who called the statement "irresponsible" and an "invitation for nuclear encounter".

"If that is what they desire, they are welcome to test our resolve. The general's doubt would swiftly be removed," Kwawja Asif said on Twitter.