Several football players in Spain have been arrested for suspected match-fixing, the league said Tuesday.

The Spanish league said the arrests were carried out by the National Police as the result of an investigation it instigated. The league said it contacted authorities about possible match-fixing involving a match in May 2018, but it did not provide details about the teams or players involved.

The league said during the 2018-19 season it informed police of eight suspected cases of “acts related to match-fixing in lower, non-professional divisions and international friendlies.”

Spanish news agency Europa Press said two of the players arrested play for first-division teams, though none of the country’s top clubs were apparently involved.

The league said it also “sent alerts” about 18 matches in which players possibly placed bets on the outcomes of games in lower and non-professional divisions.

The league thanked the National Police for the “extraordinary work done to dismantle what appears to be an organized criminal group dedicated to obtaining economic benefits through the predetermination of soccer matches.”

“This police operation demonstrates the effectiveness of integrity protection systems implemented by LaLiga to protect the cleanliness of all competitions in Spanish soccer,” the league said.