The frontman, who has netted five goals for Rafa Benitez's Championship table-toppers this season, has been linked with a move away from the club in the winter window, with Italian side Napoli said to be keen.
But the player's representative, Nenad Jestrovic, has played down that talk.
Speaking to CalcioNapoli24, Jestrovic has said that it is unlikely his client will leave St James’s Park.
He said: “It is very unlikely at the moment. The only certainty right now is that he will end the season at Newcastle United.
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“In the past there was some contact, but for now it’s out of the question."
Although he played down talk of a winter move, a summer switch was not ruled out, with Jestrovic confirming the situation would be reassessed in the summer.
“He will spend another six months in England, then well decide what to do with his future," added the agent.
Reports from Italy earlier this week had suggested Mitrovic, who is currrently away on international duty preparing to face Paul Dummett's Wales, was at the top of Napoli's January wishlist.
But since then their interest is said to have cooled, with Arsenal's out-of-favour striker Olivier Giroud favoured along with Sassuolo’s Grégoire Defrel.
Although still keen to replace injured talisman Arkadiusz Milik, it is thought the Gli Azzurri are keen to pursue more experienced targets.
And as Mitrovic, as 22, having little experience, and none whatsoever in Serie A, it is though Napoli have shleved their plans to chase the striker in the New Year.