Espanyol and Osasuna have denied wrongdoing after media reports said their La Liga game at the end of last season was being investigated for alleged match-fixing.
Reports said the two rivals had agreed beforehand on a draw. Osasuna were subsequently relegated even though they won at home to Real Betis on the final day, while Espanyol finished just above the drop zone despite losing 3-1 at Real Madrid.
"We want to make it absolutely clear that RCD Espanyol of Barcelona has had no part in any matchfixing or any irregularity," Rafael Entrena, an Espanyol vice president, said on the club's website (www.rcdespanyol.com) on Tuesday.
"We defend the purity and the sporting nature of the competition, now and always," he added.
"RCD Espanyol will collaborate actively and resolutely, both with the public prosecutor and all the sporting authorities, to take the investigation of these facts to its conclusion.
"And if the investigation shows that someone committed any irregularity they will have to face the consequences."
Osasuna president Luis Sabalza, who was not in charge of the club at the time, told a news conference on Tuesday the club "was not aware of matches being bought".
"Osasuna had no benefit because the team was relegated," he added.
However, the club did admit that they had been audited by the government sports council (CSD) at the end of last year because of unusual payments made in cash.
Osasuna did not say how much money was in question but local media said it was more than two million euros ($2.3 million).
"Right now one thing is certain which is that a sum of money was paid out in cash," club director Pedro Baile said.
"But to conclude that this money was used for a certain end, that is what needs to be proved."
The match is the second to come under the spotlight in recent months in a league where it has long been suspected that games are manipulated by teams trying to avoid relegation.
In December, Japan coach Javier Aguirre, Manchester United midfielder Ander Herrera, Atletico Madrid captain Gabi and 38 others were named in an alleged case of match fixing involving a La Liga match in the 2010-11 season. All deny wrongdoing.
Image: Espanyol's Felipe Caicedo (This image is used for representational purposes)
Photograph: Mike Stobe/Getty Images
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