VIENNA, Austria – Key flight data from high-flying aircraft mysteriously disappeared twice recently from controllers’ radar screens in Austria and some of its neighbours and the relevant EU agencies have been asked to investigate, Austria’s flight safety organization said Thursday.

Marcus Pohanka of Austro Control described the incidents on June 5 and Tuesday as unprecedented. He said the height, location, identities and other information for a total of 13 aircraft suddenly vanished over Austria – both times for about 25 minutes.

Pohanka said Thursday that several neighbouring countries had similar incidents and the EU’s Eurocontrol and European Aviation Safety Agency has been asked for a probe. He did not identify the other nations. But the daily Kurier said flight controllers in Munich and Karlsruhe in Germany, and in Prague, the Czech republic also reported related problems.

Kurier cited unnamed experts as saying interference between the aircrafts’ transponders and ground control was apparently to blame.

Pohanka declined to confirm that or to say which airlines and planes were involved. But he suggested that at least some may have been long-distance passenger aircraft, based on their high altitudes.

There was no danger at any time, he said. Pohanka said extra air controllers immediately were called to their posts and emergency measures, including establishing voice contact with the pilots and widening flight corridors, were put into effect.