At least two gunmen and a guard were killed in an attack on an Indian Air Force base on Saturday in Pathankot in Punjab, officials said, in an apparent challenge to attempts to revive a dialogue between the nuclear-armed neighbours.

Defence ministry sources said four gunmen, believed to be from Pakistan, had entered the Pathankot airbase in Punjab overnight. Two were confirmed killed in the ensuing shootout, along with the guard.

The attack came a week after Indian Prime Minister Narendra Modi made an impromptu visit to Pakistani counterpart Nawaz Sharif, in a bid to revive bilateral talks that had previously been derailed by militant attacks.

"The moment that Modi touched down in Lahore (and probably even before), something like this was doomed to happen," said Michael Kugelman, a South Asia expert at the Wilson Center think tank in Washington.

"At this point, there's sufficient goodwill in India-Pakistan relations to weather this attack. Saboteurs won't win this one," he said.

Border police chief Vijay Singh said the operation to eliminate the gunmen had lasted three hours. The airbase was being combed to determine the fate of the remaining attackers.

According to news reports, the gunmen wore army uniform. One Indian security source blamed the attack on a Pakistan-based militant group, but said it posed no threat to civilians.

The raid resembled an assault last July by gunmen on a police post in Gurdaspur that killed nine people. However, Saturday's pre-dawn attack appeared to have been much more audacious by targeting a large military facility.

One home ministry official said Punjab and Jammu states were on high alert and all defence bases had been sealed.

"Attacking an air base is a serious security threat. The new strategy of the terrorists is to identify defence bases near the border and launch attacks," said the official, who was not authorised to comment on the record.