Alexander Isak wants to explore his options for a move away from Newcastle this summer after missing their pre-season tour of Asia.

The club has selected a 30-man squad, but said the Sweden striker "misses out with a minor thigh injury".

It is understood that some of Europe's top clubs have been aware that Isak has been looking to take the next step in his career.

A source has told BBC Sport Liverpool are still interested in the 25-year-old, despite signing Eintracht Frankfurt striker Hugo Ekitike for an initial £69m.

On Saturday, Newcastle manager Eddie Howe said Isak would "absolutely" be part of the squad for the games in Singapore and South Korea.

BBC Sport has contacted Newcastle for comment.

Isak scored 27 goals in 42 appearances in all competitions for Newcastle last season.

He was left out of Saturday's 4-0 defeat at Celtic in the first of their pre-season fixtures.

Newcastle have maintained Isak is not for sale and, speaking at the weekend, Howe said he was "confident" the player will be at the club at the start of the season.

"It's difficult for me to give 100% clarity on any player," Howe said after the Celtic game.

"Alex is happy at Newcastle. He loves the players he plays with, the staff, the team, and I've never had any issue with him."

Newcastle had a £70m bid rejected for Ekitike, while they have an interest in Brentford forward Yoane Wissa.

Meanwhile, Newcastle defender Lewis Hall, who has not featured since February with a foot injury, has been included in the tour squad.

Newcastle face Arsenal on Sunday in Singapore before travelling to South Korea to play a K-League All-Star team on 30 July and Tottenham on 3 August.

Injury claim 'ridiculous' - Shearer

Newcastle legend Alan Shearer said the claims that Isak's absence from their Asia tour are injury-related are "ridiculous".

The former England striker, who scored a record 206 goals for the Tyneside club, believes they should have been open about the situation.

"It's ridiculous what Newcastle put out this morning to say he wasn't on the trip because of a slight thigh injury," said Shearer.

"If they thought people wouldn't see through that... it was disappointing.

"They should have just told the truth straight away. I understand it's a very difficult situation for them, but it is what it is.

"Eddie Howe has to use all his persuasive powers to do what he can and try to make him stay at least one more year. If that can't happen, then it is what it is.

"You have to get the very best deal for the football club, and if someone is prepared to pay north of £150m, and if he really, really wants to go, you can't step in his way."

Which teams could afford Isak?

Newcastle have been steadfast in their stance on Isak throughout the summer as Howe looks to keep his squad intact for a return to the Champions League.

The forward has three years left on his contract, and the Magpies, owned by Saudi Arabia's Public Investment Fund (PIF), are in a comfortable position with profit and sustainability rules (PSR), meaning they are under no pressure to sell.

Most Premier League clubs are unable to match Newcastle's reported £130m valuation.

Arsenal have previously been credited with an interest and have the budget, but they have since turned their attention to his fellow Swede Viktor Gyokeres and are close to finalising a deal.

Manchester City have the funds to go after Isak, but are unlikely to pursue a transfer with Erling Haaland under a contract until 2034.

Chelsea have also added strikers Liam Delap and Joao Pedro to their squad this summer.