The youngster offered a reminder to the Magpies of his value, netting a very impressive goal against Watford in the Premier League.
As the Magpies stumbled to a 1-1 draw in the game, Longstaff got his fifth senior career goal.
The 23-year-old is out of contract in the summer, with no indication he is ready to sign a new deal.
Bruce told Chronicle Live: "There's nothing I can do with anybody that gets linked. Sean is playing very well at the moment. I have been very, very pleased with him.
"So as far as I am aware, the contract details, we understand, that is for other people to sort out. Not me. But he is playing very well which is important for Sean."
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