Toon boss Rafa Benitez has made it clear there's no place for the midfielder in his plans.
The Evening Chronicle says Leeds United and Birmingham City scouts were in the stands as Colback played 90 minutes for Newcastle United's second string against Reading this week in a 4-1 win at Whitley Park.
The Magpies will attempt to off-load Colback again when the January window opens as Benitez tries to create squad space and slash the club's wage bill.
Benitez said recently: “He knew from the beginning that we have four or five midfielders and I didn't want to have six.
“We could not manage to move any more players out at the end of the transfer window and you can't train as well with as many players around in the same position.
“I did not want that.
“We have enough players in that position without Merino - Diame, Shelvey, Hayden and Saivet, even Mbemba who can also play in midfield.
“He played there in the Africa Cup of Nations."