Barton, who previously referred to the Paris Saint-Germain star as the Justin Bieber of football, has now upped his verbal tirade.
The former Marseille midfielder gave an interview with L’Equipe, in which he said he is not as good as Lionel Messi or Cristiano Ronaldo.
The £200m man was disappointing on Tuesday night as his PSG side were defeated 3-2 by Liverpool at Anfield.
Barton referenced his performances in the World Cup during his verbal assault.
“Neymar, more than a football phenomenon, is an advertising phenomenon, like the Kardashians,” Barton explained.
“I think he is the Kim Kardashian of football.
“Neymar is not the best player in the world, we saw that again in Russia.
“He is not at the level of Ronaldo and Messi, and there are many other players in front of him.”
Neymar moved to PSG in the summer of 2017 in a £200m deal, after his release clause was met.
In his first season in Paris, he scored 19 league goals in just 20 league games.
Barton also explained that he would be willing to return to Marseille as a manager, despite having only joined Fleetwood in the summer.
He explained that after his season-long loan, he understood the ins and outs of the club, and believes he is the ideal candidate for the manager’s role in the future.
“I would love to coach Marseille one day. Honestly, I could train Marseille without any problem,” he declared.
“I know the club from top to bottom. I understand the people, the culture, I know the Velodrome and I know what the club means to people.
“Many Marseille coaches did not know the club. If my trip brings me back there, fantastic.”