Pakistan officials have said that Indian warplanes did breach its airspace and drop a payload over Balakot in the country's northwest, but said there was no damage or casualties.

The National Security Council "strongly rejected (the) Indian claim of targeting an alleged terrorist camp near Balakot and the claim of heavy casualties", Foreign Minister Shah Mehmood Qureshi told a press conference in Islamabad.

"Once again (the) Indian government has resorted to a self serving, reckless and fictitious claim," he said, adding that it had been done for domestic consumption ahead of the Indian general election.

He also called the violation an "uncalled for aggression to which Pakistan shall respond at the time and place of its choosing".

Qureshi spoke after India said Tuesday its warplanes attacked a militant camp where Pakistan-backed fighters were preparing suicide attacks on its cities, sending tensions between the arch-rivals to a new peak.

A "very large number" of militants from the Jaish-e-Mohammad (JeM) group were killed in the night-time attack, according to the foreign ministry.

Pakistan has said its fighters scrambled to force the Indian jets back, and that they dropped payloads as they escaped. It did not clarify what it meant by "payloads".

There have been no reports of any casualties in Pakistan.

The escalation came after a February 14 suicide bombing claimed by JeM that killed 40 troops in Indian Kashmir, setting off a chain of threats and counter-warnings between the nuclear-armed neighbours.