Russian minister still hopeful of finding A-320 black boxes

"We are eager to find them, but have not done so yet," Igor Levitin told journalists.

According to RIA Novosti, he said various hi-tech equipment was being used in the search area where signals presumed to be from the flight recorders' radio beacons were detected.

All 113 people on board died when an Airbus A-320 operated by Armenia's Armavia flying from the Armenian capital, Yerevan, came down in stormy weather six kilometers (3.7 miles) from Adler airport, which services the popular Russian resort of Sochi.