A hijacked Ethiopian plane that landed at Geneva airport early this morning was diverted from Rome by the co-pilot, who sought asylum due to fear of persecution in Ethiopia, Swiss police spokesman Pierre Grangean said.

The unnamed co-pilot, an Ethiopian born in 1983, locked the cockpit door when the pilot went to the toilet.

He then asked to refuel at Geneva, landed the plane, climbed down from the cockpit window on a rope, and gave himself up to police.

He was unarmed and there was no risk at any time to crew or passengers, Grangean said. He is being questioned by police.

The aircraft flew through the Eastern sector of Maltese-controlled airspace on its way to mainland Europe and was closely monitored by the Maltese authorities, but it never asked to land in Malta.

In an apparent recording of a radio communication between the aircraft and air traffic control posted on the social media site Twitter, a demand for asylum can clearly be heard.

"We need asylum or assurance we will not be transferred to the Ethiopian government," the voice in the recording said, posted by Twitter user @MatthewKeysLive.