The Belgium international produced another standout display in the Partenopei's 5-0 win over Torino on Sunday, taking his tally to a combined 33 goals and assists in Serie A this term.
Mertens's form has already seen him strongly linked with both Manchester United and Chelsea, but The Sun claims that West Ham are also plotting an ambitious bid.
Napoli president Aurelio De Laurentiis recently insisted that he is confident of keeping the in-demand winger at the Stadio San Paolo, but the player's reluctance to commit means that a summer exit could be on the cards.
It is claimed that West Ham will look to match the money being offered by rivals Man United and Chelsea, as they attempt to bring a big-name player on board for next season.
Mertens, who netted five times in the Champions League proper this season, joined Napoli from PSV Eindhoven in 2013 for a fee of around £7m.