After Betis had taken a second-half lead through Alex Alegria, Barca thought they had equalised when Aissa Mandi attempted to clear a Jordi Alba shot off the line.

Referee Hernandez Hernandez did not award the goal, although replays soon showed that the ball had gone a long way over the line.

Barca boss Luis Enrique refused to condemn the officials for not giving the goal, though, instead calling for technology to be brought in to offer them a helping hand moving forward.

"I have seen the photo [of the chance] and I will say what I have always said: that referees need help," Luis Enrique said after the match.

"Whether that's with video technology or anything else available to them -- and I say it for decisions which favour us and which go against us."

Barca did eventually equalise through Luis Suarez in the final minute of the game, but if Alba's goal had been awarded they would have had 15 minutes to search for a winner.

Goal-line technology is already used in every other major European league and Aleix Vidal, who delivered the cross which led to the chance, says its introduction in Spain would mean situations like this would be easily avoided.

"You can see that the ball does go over the line," he told reporters.

"It's a really big mistake, but the fault doesn't lie with the referees. If goal-line technology was used, this wouldn't happen.

"It was clear, the Betis defender's body was completely inside [the net]."

Luis Suarez added that "the ball was clearly a metre over the line," while Neymar was less tactful in his response to the controversy, posting an image of the incident on Instagram, along with the caption "HAHAHAHAHAHAHAH."

Betis coach Victor Sanchez did not comment specifically on the decision, but did add his voice to the growing calls for referees to be given more help.

"A referee's job is really difficult," he said. "It's tough and as we're all human, we can't get everything right.

"I'm in favour of help, of course. Everything which can be incorporated to the game and can help, while not affecting the flow of matches, of course should [be introduced]. Everything is evolving and football has to be open to [evolving] as well."