Spanish side Villarreal let the 26-year-old centre forward join Italian outfit Salernitana on loan in the summer, with an option to buy.
Dia has been impressive since joining Paulo Sousa’s side, scoring 16 goals and laying on six assists in his 33 appearances.
The Spanish outfit inserted a €12m option to buy clause in Dia’s contract and Salernitana want to trigger that option to keep the forward at the club.
But his excellent performances have drawn interest from Premier League outfits West Ham and Everton, raising the prospect of Salernitana signing him and then selling him soon after.
Both Everton and West Ham have struggled in the goalscoring department this season and are claimed to hold an interest in Dia.
Salernitana want to keep hold of Dia into next season but, according to French outlet Foot Mercato, will let the striker make his own decision.
Everton were one of the clubs that expressed an interest in Dia during the winter transfer window and they have retained their interest in the 26-year-old.
And it remains to be seen what Dia has in mind regarding his move in the upcoming transfer window.
