The Senegal international, who has scored 16 Premier League goals this season, is seen in London as a possible replacement for Didier Drogba, who will be out of contract in the summer.
Frank Lampard and Michael Essien could be leaving in the summer, while Fernando Torres has failed to justify his £50million price-tag.
Ba is understood to have a £7m release clause in his contract.
Demba Ba : "It is rumours like you get in football.
"I'm sick of it really, as I want to stay at Newcastle, but I cannot stop the rumours.
"I am happy with Newcastle and I enjoy being here and playing for the Toon Army. I enjoy being in this team.
"We have a good team spirit and I love the North East, where I have my country-mate, Papiss Cisse."