The 24-year-old has been with Les Parisiens since 2012 and has played a key role in their run of four straight Ligue 1 titles.
His ability on the ball has seen him regularly linked with a move away from the Parc des Princes, with Juventus believed to be keen, while a reunion with former Italy boss Antonio Conte at Chelsea has also been mooted.
Current Azzurri coach Ventura has suggested he would like to see the playmaker feature for a club in what he perceives to be a more competitive league.
With PSG so dominant, the boss believes the former Pescara man is not being tested regularly, and as a result, could be viewed as being under-prepared when it comes to international selection.
“The problem is that he doesn’t play in Italy, but in France,” Ventura said. “The rhythms are different; the strength of his team is so high that he never gets put in difficulty.
“He must get used to putting 100 per cent into matches.”
Southampton have announced plans for a two-week tour of China as part of their pre-season preparations for the 2018-19 season.