The Finnish Transport and Communications Agency Traficom has revealed the details of a "serious incident" that occurred on 13 May at Helsinki-Vantaa airport when a drone flew very close to the wing of an airplane during take-off.

The agency said that the crew of a commercial aircraft observed a remote-controlled drone near the right wing while they were at an altitude of approximately 400 metres.

In the statement, Traficom emphasised that anyone operating a drone must be aware of prohibited and restricted airspace areas in accordance with EU legislation.

"A drone hitting the wing of an aircraft may cause significant damage, and the situation in question was very alarming," Traficom Director Jari Pöntinen said.

The drone was flying inside the restricted UAS geographical zone established to protect Helsinki Airport at the time of the incident, and the drone operator did not have a permit issued by air traffic control, Pöntinen added.

There is currently no information about the identity of the drone operator, although an investigation is ongoing, Traficom said, but finding the operator will be extremely difficult.