Spanish club Rayo Vallecano said Monday they were the victim of "football terrorism" after vandals cut the cables to stadium lights and forced a match with Real Madrid to be postponed.
The derby clash at Estadio de Vallecas in Madrid was scrapped on Sunday evening after the blackout, leaving fans stranded outside, and the clubs agreed to try again at 7:45 pm (1745 GMT) on Monday.
"We suffered sabotage, an attack. We are facing a new kind of terrorism, football terrorism," Rayo Vallecano chairman Raul Martin Presa told a news conference.
"We have never seen anything like this at a club."
Rayo Vallecano, displaying photographs of the severed cables to journalists, said repairs were going well and lighting tests would be held shortly to confirm the game could go ahead.
"The 57 cables leading to the lights of one of the stands were cut and the 12 fuse boxes they come from were interfered with," Rayo Vallecano managing director Luis Yanez said.
Police confirmed that the act was deliberate, the central government representative for the Madrid region, Cristina Cifuentes, told ABC Punto radio.
"Forensic police made a first inspection on Sunday evening... and they returned this morning," she said. "It has apparently been confirmed that there was sabotage."
Police were trying to lift fingerprints from the scene and checking security cameras in case the culprits were filmed, she said.
The sabotage was "despicable", Cifuentes said. "Those responsible must be found and punished," she added.
Despite the chairman's forceful language, officials did not appear to seriously suggest that the sabotage was carried out by terrorists.
Spanish football league deputy head Javier Tebas said Rayo Vallecano was not to blame.
"This should be fixed during the day today, but if they cannot play tonight Rayo has no responsibility for what happened," he told Radio Marca.
"Since we are dealing with sabotage, even if we cannot play today the match will not be treated as a loss for Rayo."
Fans were not allowed into the stadium for security reasons Sunday for a match which had been due to start at 9:30 pm (1930 GMT).
Real were desperate for a win in the match having made a dismal start to the season to languish eight points behind leaders Barcelona after just one win in four games.