By BBC-Pakistan says it has shot down two Indian Air Force jets in a major escalation of the Kashmir conflict.
A spokesman said one plane had fallen in Pakistani territory and two pilots had been captured. Pakistan also denied reports one of its jets was shot down.
India has confirmed the loss of an MiG21 fighter and said a pilot was missing. It said it was investigating reports of his capture.
Both India and Pakistan claim all of Kashmir, but control only parts of it.
The nuclear powers have fought three wars since independence from Britain in 1947. All but one were over Kashmir.
The aerial attacks across the Line of Control (LoC) dividing Indian and Pakistani territory are the first since a war in 1971.
They follow a militant attack in Kashmir which killed 40 Indian troops – the deadliest to take place during a three-decade insurgency against Indian rule in Kashmir. A Pakistan-based group said it carried out the attack.
The BBC’s Soutik Biswas, in Delhi, says the challenge for India and Pakistan now is to contain the latest escalation before things get completely out of control.
What’s the latest?
Pakistan’s information ministry published but subsequently deleted a video purporting to show one of the Indian pilots that the Pakistani military says it has captured.
In the video, the pilot – who is blindfolded and appears to have blood on his face – identifies himself as Wing-Commander Abhinandan.