India's army says its troops have been fighting Pakistan-backed armed militants in Indian-administered Kashmir for more than a week.
Some 30 to 40 fighters have crossed the Line of Control (LoC), which divides the region, senior army officer Gurmeet Singh said. Pakistan has denied India's claim, saying it was a "blatant lie".
Claimed by both countries, Kashmir has been a flashpoint for over 60 years.
Bilateral ties have been strained over recent clashes in the disputed region.
Last month, at least 10 people were killed when militants stormed a police station and an army camp in the Poonch area of Indian-administered Kashmir.
India has a large security presence in Kashmir with tens of thousands of police and paramilitary forces deployed in the region.
"The army is fighting the largest group of infiltrators including some special troops on the line of control with Pakistan in Indian territory. It's one of the longest operations in Kashmir," Lt Gen Gurmeet Singh said.
Some 10 to 12 infiltrators have been killed by Indian soldiers, Mr Singh said, adding that another group of 10 men had tried to cross over on Tuesday.
Mr Singh told reporters on Wednesday evening that Indian soldiers first encountered up to 40 militants on 24 September in an abandoned village called Shala Bhata near the line of control.
"There is no question of our territory being taken over," he said, adding that the army was in "total control of the operation".
On Thursday, Pakistan's army denied India's charge.
"No such thing happened at all. This is a blatant lie. We totally deny this baseless allegation," Press Trust of India quoted a Pakistani military spokesperson as saying.
The latest fighting is taking place days after Indian PM Manmohan Singh and his Pakistani counterpart Nawaz Sharif pledged in New York to work together to halt a recent upsurge of violence in Kashmir.
During the weekend Mr Singh told the UN General Assembly Pakistan had to stop being "the epicentre of terrorism".
India has long accused Pakistan of sponsoring militants in the disputed region. However, violence has declined overall since the early 2000s, despite a recent spike.
But relations plunged again over the 2008 Mumbai attack.
Mr Singh has expressed disappointment in the Pakistani response and reiterated a call for Pakistan to rein in militants in his UN speech.
Mr Sharif swept to power in May with pledges to improve ties with India.