Home Minister P Chidambaram said the attack on Pakistan Air Force base has again highlighted the fact that India lives in a troubled neighbourhood.

"I have described our neighbourhood as a troubled neighbourhood. This incident once against points to that conclusion that our neighbourhood is a troubled neighbourhood," he said at a press conference here when asked to comment on the attack in Pakistan.

"We have to remain constantly on vigil and we remain vigilant round the clock," he said.

The Home Minister said India was "not happy" about the incident that took place in Karachi. "In fact, we are sad that lives are lost. But that is today a troubled State.

Noting that any incident of terrorism in the region certainly must be viewed gravely, he said, "We must increase our vigil. Therefore we remain alert and we have alerted the states based on whatever intelligence we have".

Asked to comment on media reports that Taliban chief Mullah Omar had been killed in Pakistan, Chidambaram said there were contradictory versions and "we have to wait and see whether that report is correct".

He, however, said India had "some information" on the movements of Mullah Omar. "But that was only information we had picked up. But, today Afghan authorities have disclosed that he was killed," he said.