Croatian Prime Minister Andrej Plenkovic said on Friday the most important thing was to establish who launched the drone which crashed in Zagreb last night and whether it reached Croatia by accident or deliberately.

He informed the leaders of other EU member states at a summit in Versailles about the incident and said Croatia had experts for such situations.

“We will share with others what they find out,” he said at the end of the summit. “They received this information with maximum seriousness. It’s not usual for an aircraft that is 14 metres long and weighs six tonnes to fall on a capital city.”

Asked if NATO had tracked the drone and if Croatia was informed about it, Plenkovic said, “If someone had been notified, the reaction would have been different. Our planes would have taken off and reacted.”

This was a totally unforeseen situation, he added.

A NATO spokesman told the Croatian news agency Hina the alliance’s air defence tracked the drone’s flight path.

The Soviet-made drone arrived in Croatia from Hungary, where it came from Romania. It was in Croatia’s airspace for six or seven minutes before crashing in a residential area in western Zagreb.