New Delhi, April 22 (IANS) The Palam airport here was put on high alert Tuesday evening when an Indian Air Force Boeing 737 carrying Prime Minister Manmohan Singh was preparing to land after the air traffic control noticed a sudden blip on their radar screen. But the plane touched down safely, officials said. The blip, however, caused a scare and delayed the landing by 16 minutes as the pilots switched off the aircraft’s instrument landing system and manually guided the plane on a changed flight path during the final approach.

The blip - “an unidentified target”, as one official put it - appeared when Singh’s plane entered Delhi’s airspace. The prime minister was returning to the capital from Jamshedpur in Jharkhand.

“All the security agencies were put on high alert as soon the blip appeared,” an air traffic control official told IANS, speaking on the condition of anonymity.

“The flight got delayed by nearly 16 minutes. The blip has not been identified yet. The Directorate General of Civil Aviation and security agencies are probing the matter,” the official added.