The Dundee Evening Courier report says a six-figure fee plus a significant sell-on has been agreed for the 24 year-old Cameroon international.
Posh were first linked with a move for Fuchs in August. He has played 47 times for Dundee United since moving to Tannadice from Israeli side Maccabi Haifa in January, 2020.
Fuchs previously played in France with Sochaux and Spain with Alaves.
Blackpool and Wigan are also understood to have been tracking the player.
The PT’s Scottish football expert Kevin Swann said in August: “Fuchs is a strong defensive type. Dynamic, wins the ball, can take it under pressure, passes it on. Not bad going the other way either! Has played particularly well in a few games against Rangers and Celtic who were also rumoured to be after him.”