The announcement by the Canary Islands emergency services set off a flood of breaking news alerts of a possible disaster by Spanish and international media.
The islands’ emergency services said on their Twitter account shortly after 1500 GMT on Thursday (0200 AEDT Friday) that air traffic controllers had confirmed a plane fell into the sea two nautical miles off Gran Canaria.
The false announcement spawned unfounded reports online that it was a Boeing 737 passenger jet.
Minutes later the emergency services corrected the report.
“It has finally been confirmed that it is not a plane, it is a tugboat pulling another vessel,” a spokeswoman for the service said.
The Spanish airport authority AENA added in a tweet shortly afterwards: “False alarm: no plane has disappeared off the coast of Gran Canaria.”
Spanish media later published a photograph of what they said was the vessel in question: a tugboat with a long yellow crane whose outline resembled that of an aeroplane.