(CNN) -- Five Indian soldiers were killed in an attack on the Line of Control in Indian-administered Kashmir early Tuesday, India's government said.
Indian Defence Minister AK Antony told parliament the ambush was carried out by approximately 20 "heavily armed terrorists along with persons dressed in Pakistan army uniforms."
The chief minister of Indian-administered Kashmir denounced the attack on Twitter.
"These incidents don't help efforts to normalise or even improve relations with Pak & call in to question the Pak Govt's recent overtures," Omar Abdullah tweeted Tuesday morning.
Pakistan denied playing a part in the attack.
"No such incident has taken place," the military said, while Pakistan's ministry of foreign affairs also rejected the claim.
"These are baseless and unfounded allegations. Our military authorities have confirmed that there had been no exchange of fire that could have resulted in such an incident," a statement from the ministry said.
The incident could cast a shadow on the resumption of India-Pakistan talks when the prime ministers of the two countries meet in New York for the U.N. General Assembly in September.
The two South Asian neighbors have had a cease-fire along the de facto border, known as the Line of Control, since November 2003. But it has been violated repeatedly, with both sides accusing the other of offenses.
Tuesday's ambush came close on the heels of the Indian army's operations against militants infiltrating into the Indian side of Kashmir, resulting in the deaths of 13 militants last week. One Indian army soldier was also killed in one of the gunfights in north Kashmir's frontier Kupwara district, according to the defense spokesman.
"This action is a likely consequence of frustrations of the terrorists' tanzeeems (outfits) and Pak army due to successful elimination of 19 hardcore terrorists in the recent months of July and August along the Line of Control and in the hinterland of Jammu and Kashmir," the defense ministry statement said.
India's defense ministry said Tuesday that it has recorded 33 ceasefire violations by the Pakistanis between February and July -- resulting in one death and three injuries.
The conflict over Kashmir dates back to 1947, after Britain relinquished control of the Indian subcontinent, giving birth to modern India and Pakistan.
Kashmir was free to accede to either nation.
Maharaja Hari Singh, the ruler of the kingdom at the time, initially chose to remain independent but eventually opted to join India, thereby handing key powers to the central government in New Delhi.
In exchange, India guaranteed him military protection and vowed to hold a popular vote on the issue.
The South Asian rivals have fought two full-scale wars over the territorial issue.
Islamabad has always said that majority-Muslim Kashmir should have been a part of Pakistan. A United Nations resolution adopted after the first war called for a referendum allowing the people of Kashmir to choose which country they wanted to join, but that vote for self-determination has never been held. Pakistan wants that referendum to take place.
India says that Pakistan lends support to separatist groups fighting against government control and argues that a 1972 agreement mandates a resolution to the Kashmir dispute through bilateral talks.
CNN's Neha Sharma reported from New Delhi, with Mukhtar Ahmad reporting from Srinagar. CNN's Shaista Aziz in Islamabad, Pakistan; and Aliza Kassim in Atlanta contributed to this report.