The 24-year-old is under contract at St James' Park until 2023 but has been the subject of speculation linking him with a move to Chelsea, as the Blues look to overhaul their playing squad this summer.
Lascelles, who is said to be valued at £30m, has yet to receive an England cap but is one of the most highly rated young defenders in the country.
According to manager Rafael Benítez (via the Mirror), however, Lascelles is not distracted by speculation over his future and remains firmly focused on the rest of this season with Newcastle.
When asked about his captain's future in his press conference, the Spaniard said: “He’s happy, training well, he’s improving, he’s focused.
Jamaal Lascelles made Harry Maguire look like an absolute side dish yesterday by the way— Matty Crow (@Crowy96) April 8, 2018
“You can’t stop speculation about players but I was talking with him for a while last week, the focus is just trying to improve his game.
“I think at the moment he knows he has to continue progressing and learning but he is quite happy here.”
Newcastle remain firmly focused on cementing a top half finish in the Premier League, and Lascelles' leadership from the heart of the defence has been crucial to elevating the side to the healthy position in which they now find themselves.
The future of Lascelles could depend on whether Amanda Staveley's takeover of Newcastle goes through in the summer. It remains a possibility, but the ambition and potential of the club will surely play a huge part in Lascelles' future as a Magpie.