The aircraft roared over Islamabad [Images], the nearby garrison city of Rawalpindi and other cities this afternoon as Air Force spokesman Air Commodore Humayun Viqar Zephyr said in a statement: "in view of the current environment, PAF has enhanced its vigilance."

The brief statement from the air force did not give any more details. Residents in the capital made panic calls to media stations to ask about the low-flying aircrafts.

The air sorties by the PAF came a day after External Affairs Minister Pranab Mukherjee [Images] said India is keeping "all options open" to deal with the aftermath of the Mumbai terror attacks.

India has blamed Pakistan-based elements, including the Lashkar-e-Tayiba [Images] terror group, for the attacks and asked Pakistan to take action against them.

Congress party chief Sonia Gandhi [Images] too has said that India could give a "befitting reply" to those involved in the Mumbai attacks.

The two countries were involved in a spat last week over alleged violations of Pakistani airspace by Indian warplanes.

Pakistan lodged a formal protest that Indian jets had violated an agreement on airspace violations in the Pakistan-occupied Kashmir and Lahore [Images] sectors, a charge flatly denied by India.

Indian High Commissioner Satyabrata Pal is in Delhi [Images] to attend a meeting of all Indian envoys and Pakistani High Commissioner Shahid Malik is in Islamabad for consultations.