Even as India on Tuesday said the United States commercial aircraft, flying from Karachi to Male, had strayed into Indian airspace due to the wrong flying path provided to it by the Pakistan Air Traffic Control, Civil Aviation Minister Shahnawaz Hussain made a startling disclosure.

"Even today an unidentified plane was sighted 180 nautical miles off Chennai and it did not respond to our signals," Hussain said.

He said that India would complain to the International Civil Aviation Organisation (ICAO) about Monday's incident in which the Pakistani ATC gave wrong directions to the US cargo plane. "ICAO should probe the matter," the minister said.

Following Monday's incident, defence sources said, a MiG-21 fighter aircraft was on Tuesday airborne to ensure that the IAF had an 'operationally ready airborne platform' to meet any emergency.

Hussain told reporters in Delhi that the 11-member crew of the Boeing 757, which was forced to land in Mumbai on Monday evening, had been questioned by officials of the Directorate General of Civil Aviation.

He said the Intelligence Bureau had completed its inquiry but he refused to give any further details.

The ATC immediately informed the IAF and the matter was also brought to the notice of the defence and external affairs ministries, he said.

The crew of the aircraft was confined to the reserved Lounge of the Sahar Terminal at the Chhatrapati Shivaji International Airport.

Intelligence Bureau officials questioned Captain John Burg and his team after they had been cleared by the Indian Air Force at 0200 IST on Tuesday.

The IAF had forced the Boeing 757 belonging to Conco Corporation with registration number N610G, flying to Male from Karachi, to land in Mumbai after it was found flying over Indian airspace without permission.

United States Vice Consul General Michael Cole met the crew led by Captain John Burg even as the aircraft was towed away from the isolated bay to be parked at the international terminal, airport officials said.

The plane was flying on the N-519 route segment which is not permitted between 0600 to 1800 IST and the Boeing violated the airspace before 1800 IST on Monday, they said.

Conco Corporation is an aviation and engineering company handling chartered flights and providing engineering services out of Nashville. This Boeing had taken off from the US on January 31 and after re-fuelling stops at two places, including Munich, it reached Karachi on Monday.