Sevilla are to take legal action against Vitolo, Atletico Madrid and Las Palmas in the wake of his controversial transfer to the Spanish capital.
Atletico last week confirmed a five-year deal to sign the winger despite being restricted by a transfer ban that is due to end in January.
Vitolo will play for Las Palmas for the first half of next season before he registers with Atletico in January.
The complex transfer came two days after Sevilla president Jose Castro claimed the 27-year-old had in fact signed a new five-year deal with his club.
A statement posted on Sevilla's official website following a meeting of the board of directors confirmed: "The board of directors have agreed to take legal action against those who have intervened in the departure of Vitolo from the club, they are the player himself, his father, the representation agency Bahia and the clubs Atletico Madrid and Las Palmas.
"The club has already entrusted two law firms to the case to defend the interests of the club. Sevilla FC reached a renewal agreement with Vitolo on July 10, endorsed by written documentation, which the player decided to break unilaterally."
Vitolo joined Sevilla from Las Palmas in 2013 and scored 28 goals in all competitions for the club, winning the Europa League three times.