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Isak is not a part of Eddie Howe's travelling party for Newcastle's pre-season tour of Asia amid mounting transfer speculation surrounding the Sweden international.

The 25-year-old was also left out of the Magpies' squad for last week's friendly against Celtic.

Although Newcastle put Isak's absence from its trip to Asia down to a minor thigh injury, reports emerged on Friday that the striker had asked to leave the club.

Despite signing Hugo Ekitike from Eintracht Frankfurt for an initial £69 million ($141.2 million) plus up to £9 million ($18.4 million) in add-ons, Liverpool is reportedly the frontrunner for Isak's signature.

It is reported that Newcastle would demand around £130 million ($266 million) to consider parting with Isak.

"If we lost any player it would upset our tight-knit group that's been together for two or three years now," Burn said of how damaging it would be if Isak was to depart.

"Any player that leaves, it doesn't help but from our point of view, we're just going to control what we can control. We're looking forward to getting Alex back when he's fit.

"It's a question for Alex to answer. He's obviously a big player for us, but we do have a lot of quality in the squad as well.

"Bringing Anthony [Elanga] in as well, which I think was a great signing."

Last term, Isak became the first Newcastle player to score 23 goals in a Premier League campaign since Alan Shearer in 2001-2002 (also 23), and has been a key part of the Magpies' recent success.

He scored Newcastle's second goal in its 2-1 victory over Liverpool in the Carabao Cup final back in March, sealing the club's first domestic trophy since the 1954-1955 FA Cup.

Across 109 appearances in all competitions since his arrival from Real Sociedad in August 2022, Isak has scored 62 goals and provided 10 assists for his team-mates.

Bruno Guimaraes said he was unaware of Isak's desire to leave the club, but reaffirmed that Newcastle want to keep their "best players".

"Of course, he's a top player, and we know everything going on around him, but he's [staying at home] to do some physical treatment," Guimaraes stated.

"We want to keep our best players. That's my point, and what I want to say is that I don't know what anyone has seen, but for us, he's not here because he's injured.

"He's a top striker. His last three seasons speak for themselves, a top player.

"But as much as I know, he's stayed at home because of his injury. It's not for me to speak about him, it's something the club will take care of."

Newcastle's pre-season tour of Asia begins with a clash against Arsenal in Singapore before games in South Korea against a K-League All-Star team and Tottenham Hotspur.