Nervous police in Egypt have detained a bird on suspicion of being a spy.

The stork was taken into custody after touching down in the Nile River in Qena, central-eastern Egypt. An electronic device attached to its feathers made a local fisherman think it was an undercover enemy agent.

He seized the bird and took it off to a local police station. Police who examined the mystery gadget at first feared they were dealing with a bomb or a surveillance tool.

It was not until wildlife experts were called in that the facts became clear: the suspected explosive device was actually a movement tracker.

Researchers in France had attached the device to the bird before it set off on its migrational journey. According to reports, the device stopped working when it crossed the French border.

But the stork has not yet been granted its freedom by the authorities in Egypt because it must stay behind bars until local state prosecutors grant it permission to fly off.

Authorities in the country are on high alert following the removal of President Mohammad Morsi by the army. Civil unrest broke out in response to the coup in July, causing hundreds of deaths.