Newcastle United scouts were reportedly in attendance for the game between Lech Poznan and Wisla Krakow on Sunday, which ended 0-0.
The Hungarian left the Magpies in 2012 after spending over 4 years at the club, moving to United when he was just 17.
Despite his many years at the club, Kadar only made 13 appearances for the side before leaving for Dutch side Roda.
The defender then had a spell at Hungarian side Diosgyori before joining current club Lech Poznan in January 2015.
He has also become a fixture of the Hungarian national side since leaving Tyneside, impressing during Euro 2016.
Kadar was heavily linked with Russian side Lokomotiv Moscow over the summer however the deal fell through, leaving the door open for a return to Newcastle.
Newcastle boss Rafa Benitez did recently confirm that Newcastle would look to be active during the January transfer window in an effort to solidify their push for promotion.
Newcastle United fans, what do you think of the news? Is Kadar the player Newcastle need to help their promotion push? Let us know what you think below!