Merten, who moved to the club in June from PSV, claims that the Partenopei coach has already asked him to encourage his fellow Belgian to make the switch to Serie A.
Furthermore, Mertens himself wants his international team-mate to move to Napoli, with Vermaelen having fallen behind Per Mertesacker and Laurent Koscielny in the pecking order at the Emirates Stadium.
"I have already told Vermaelen to come to Napoli 10 times," Mertens, 26, told Knack.
"The city is magnificent and even Benitez asked me to convince Vermaelen to come here.
"But Arsenal is a great club and it won't be so easy for him to leave."
Vermaelen made only two league starts this season with the centre-back having previously stated a desire to play regularly in the run-up to World Cup 2014.