Indian aircraft violated Pakistan's airspace Saturday but were chased back over the border by Pakistani fighter jets, an Air Force spokesman here said.

The alleged incident comes amid heightened tensions between the nuclear-armed rivals over last month's deadly attack in Mumbai. India has said the attack, which left more than 170 people dead, had roots in Pakistan.

Pakistan Air Commodore Himayun Viqar said the Indian aircraft crossed over the border some one to three miles in Pakistan-controlled Kashmir and over the eastern city of Lahore.

He would not say how many Indian aircraft were involved or give the exact time but said that Pakistani jets responded, forcing the Indian aircraft to turn back.

Attempts to get Indian comment were not immediately successful early Sunday morning.

However, in a statement, Pakistan Information Minister Sherry Rehman said the Indian Air Force had told Pakistan the incursion was "inadvertent."

"Our forces are on alert," Rehman said, adding, "There is no need for undue alarm."