A big portion of Spanish airspace has been shut down over fears that debris from a large and out-of-control Chinese rocket could rain down across the European country.

On Friday, the European air traffic control agency Eurocontrol warned that normal flight operations would be disrupted across Spain, including Madrid, during a window of highest risk for when the rocket is expected to fall to Earth.

The rocket, known as CZ-5B was launched into space by China on October 31 but has failed to maintain Earth orbit and is expected to reenter the atmosphere over the North Atlantic.

Space experts have calculated the trajectory of the 23-tonne rocket that will see it fly over Portugal and Spain and it is feared that debris from the rocket could fall. It is the largest rocket to have fallen to Earth in an uncontrolled reentry in years.

“As this is an uncontrolled re-entry, it is difficult at this point in time to exactly predict the trajectory of the debris and where the parts will fall,” Eurocontrol warned airlines and members of the public on Friday.

Madrid and Barcelona could be impacted, and in a worst-case scenario, Marseille, Rome and Athens could be at risk.

An aviation NOTAM or ‘Notice to Airmen’ warns pilots that it is “critical that flight crew members report any observed falling space debris”.

Spanish flag carrier Iberia warned on its Twitter account that flights could be affected throughout the day. Even after the threat has passed, flight operations could take some time to return to normal.