Cadiz, who were relegated to the Segunda Division B (third division) at the end of the campaign have accused two of their former rivals of predetermining match results.

And the federation (RFEF) have confirmed they are taking the matter seriously.

A statement on the RFEF website read: "The Competition Committee of the Spanish Football Federation have opened a confidential investigation, under the protection of what is decreed in article 38 of the Royal Decree 1591/1992, in relation to the complaint presented by Cadiz CF, relative to 'a presumed infraction of article 75 of the RFEF Disciplinary Code, consisting of the predetermination of results'.

"In today's resolution, the Committee have agreed to send a copy of the aforementioned complaint to all the clubs that were in the Liga Adelante (Segunda Division) in the 2009/2010 season, with the aim that they can present the allegations that they consider appropriate."

The RFEF also confirmed they have asked the courts for a copy of tape recordings which came to light during a separate court case involving Enrique Ortiz, the major shareholder in Hercules, who were promoted to the top flight last season.

The recordings are believed to prove crucial to Cadiz's case and could see a shift in current Primera and Segunda Division clubs, with the new season less than three weeks away.

Hercules, Real Betis and Levante all finished on the same number of points last season, but Betis lost out on promotion with the worst goal difference in meetings between the three.

The group Por nuestro Betis, which is composed of fans and shareholders of the club, have urged FIFA and UEFA to look into the matter as well.