Spanish politicians and victim association representatives gathered in Barcelona's airport Wednesday to unveil a plaque in memory of those killed when a Germanwings plane was flown into a mountain by its co-pilot while en route from Barcelona to Duesseldorf last year.

Acting Prime Minister Mariano Rajoy and regional Catalonia government President Carles Puigdemont attended the ceremony outside Barcelona's Terminal 2 on the eve of the accident's first anniversary.

All 150 people aboard were killed in the crash. Most of the victims were German or Spanish.

Families, rescuers and aviation officials are to attend an anniversary ceremony Thursday in Le Vernet, France, close to where the plane crashed.

In a speech, Rajoy highlighted the excellent cooperation between French, German and Spanish authorities in the days following the tragedy.

He said that investigations into the crash were helping bring about measures to avert similar tragedies, adding that the "best way to honor the victims is the commitment to preventing this type of tragedy happening again."

After the ceremony, wreaths were laid at the foot of the plaque

The ceremony was attend by French and German embassy officials, members of the Association of Victims of Germanwings Flight 9525 in the Alps and representatives of Spanish police forces and emergency services that helped victims' families after the crash.