It said modern radar and navigational systems have been installed at Graf Ignatievo airport, near the city of Plovdiv in central Bulgaria, giving it "friend or foe" recognition capabilities to identify incoming aircraft.

"We have reached maximum compatibility with our NATO partners," Bulgarian President Gueorgui Parvanov said at a ceremony.

Sofia was invited to join the North Atlantic Treaty Organisation last November.

Bulgaria last April selected Canada's Intelcan Technosystems, to carry out the modernisation over French group Thales, BAe Systems of the UK and Alenia-Marconi, an Anglo-Italian consortium. Intelcan is also updating radar equipment at Krumovo military airport, also near Plovdiv.

SPACE.WIRE