The LFP denied a report on radio station Cadena Ser that it had informed anti-corruption investigators of possible cases of match-fixing in recent La Liga and second-tier games.
The broadcaster also alleged European football's governing body UEFA was investigating suspect betting patterns. It did not identify the source of its information or provide details of which matches were involved.
A separate report on Cadena Cope radio, which cited an anonymous source in the LFP, raised doubts about Sporting Gijon's 3-0 win at Espanyol at the weekend which prompted a furious response from both clubs.
Gijon president Manuel Vega-Arango called a news conference at which he said the Asturians, who are second from bottom with three games left and fighting to avoid the drop to the second division, would be taking Cope to court over their allegations.
"These things disgust me and I am extremely angry," Vega-Arango said.
"We are a modest club in economic terms but... with a sensational fan base who does not deserve these things which is why we are not going to let it go."
Espanyol CEO Joan Collet, whose side is chasing a lucrative place in Europe next season, said the Barcelona-based club would be doing "everything necessary to defend its honour".
Espanyol's head of legal affairs Rafael Entrena said the club would take 24 hours to mull over its next move.
"This is a very grave issue and the club will act accordingly," he added.
TASK FORCE
Several countries have had to deal with allegations of match-fixing in football in recent weeks, including Turkey, China and Italy, where the government has set up a match-fixing task force in response to a number of high-profile cases.
Nan Yong, the former head of Chinese football , was this month charged with taking 1.48 million yuan ($234,500) in bribes, state media said, the latest episode in the nation's drive to clean up widespread corruption in the sport.
The LFP published a statement earlier on Monday in reaction to the Cadena Ser and Cadena Cope reports in which it denied it had denounced suspected match-fixing.
"As things stand the LFP has not lodged any formal complaint about irregularities relating to the normal evolution of the first or second division championships in the current season," the statement said.
League officials had met up with representatives of the state prosecutor several weeks ago as part of their efforts to prevent "any situation developing which might be outside the bounds of legality," it added.
The meeting was held to coordinate any "preventative or investigative action".
"As already expressed on multiple occasions the LFP is dedicated and strongly committed to the fight against competition fraud and will use all the means at its disposal to avoid it," the league added.
UEFA did not immediately respond to a request for comment.
