Complaints were first brought to the police’s attention about possible match-fixing in a La Liga fixture which took place in May 2018.
The Spanish league says the match-fixing was possibly conducted by "an organised criminal group."
Since those complaints, La Liga has reported eight more possible match-fixing cases to the Spanish authorities.
A La Liga spokesperson said: "During the 2018/19 season, La Liga has filed eight complaints with the General Commissioner of the judicial police for alleged acts related to match-fixing in lower divisions of Spanish football and international friendlies played in Spain.
"This police operation demonstrates the effectiveness of integrity protection systems implemented by La Liga to protect the cleanliness of all competitions in Spanish football."
The police have stated the investigation is ongoing.
