PARIS: A plan has been hatched to guide a killer whale adrift in France's River Seine back to the sea — using orca sounds, local officials said on Friday.

Following a meeting with national and international scientists, including marine mammal specialists, the local prefecture said it would monitor the killer whale from a distance with a drone while emitting orca communications in an attempt to guide it back to the sea.

"The use of these non-invasive methods, from several hundred meters (feet) distance, will make it possible to avoid using ships in the immediate proximity of the animal, which could aggravate its stress and endanger it survival, as well as the safety of rescuers," said the Seine-Maritime prefecture in a statement posted on Twitter.

The whale, whose health is deteriorating in fresh water, strayed from the ocean earlier this month, and is at risk of dying. 

The 4-metre (13-foot) orca, identified as a male, was first spotted at the mouth of the Seine on May 16 between the port of Le Havre and the town of Honfleur in Normandy, before it travelled dozens of kilometres (miles) upstream to reach west of the city of Rouen.

Several French media outlets showed footage of the killer whale in the river, its dorsal fin sticking out of the water and its distinctive black and white colouring showing as it comes up for air.