The 31-year-old spent last season on loan at the Serie A side, making 40 appearances in all competitions, as Simon Mignolet became Brendan Rodgers’ first-choice goalkeeper at Anfield following his summer switch from Sunderland.
Reina, who is currently with the Spain squad at the World Cup, has previously stated he would be happy to stay at Napoli but it now appears he will have to consider his options elsewhere.
Atletico Madrid and Barcelona have been among the other clubs reported to be keen on his services after Benitez confirmed he would be leaving the Stadio San Paolo.
Asked if Reina’s future belongs in England, Benitez told talkSPORT: "Yes. Pepe has two years left on his contract at Liverpool.
"He has to go back and he’ll stay there. We can’t afford Pepe’s wages.
"The Premier League is a very big league and, in Serie A, we don’t pay big wages like in England. He will have to fight for his position at Liverpool."