Barnetta, a regular in the Leverkusen side, is believed to have attracted interest from the Magpies, Wigan and Sunderland.
The 26-year-old has spent the last seven seasons in the Bundesliga, having arrived at the BayArena from native outfit St Gallen in 2004.
He spent a brief spell on loan at Bundesliga rivals Hannover before returning to establish himself in the German club's first-team.
The Leverkusen man scored both of Switzerland's goals in quick succession during their 2-2 Euro 2012 qualifying draw with England back in June.
Source: Team Talk
Source: Team Talk