Isak has discussed his decision with the club's leadership, as reported by Daily Mail chief football correspondent Craig Hope.
Liverpool have emerged as the leading contenders for the striker's signature this summer, taking over from Arsenal, who are now nearing a deal for Isak's fellow countryman, Viktor Gyokeres.
The Reds are reportedly prepared to meet the Magpies' £120 million asking price, although they are also encountering competition from Saudi Arabian club Al Hilal.
This news follows the announcement on the Newcastle website that Isak will not travel with the team to Singapore and South Korea, citing a minor thigh injury as the reason for his absence.
This directly contradicts manager Eddie Howe's statement over the weekend, when he asserted that the Swede would "absolutely" be traveling to Asia. Howe made these comments after Isak did not participate in Newcastle's 4-0 friendly defeat to Celtic, while the forward has been training alone in recent days.
These developments have intensified speculation that the 25-year-old is on the verge of finalizing a transfer away from St James' Park, but today's news has confirmed for the first time that Isak is actively seeking a move.
Newcastle will be without their top scorer from the 2024/25 season in Asia, where they are set to face Arsenal in Singapore, before heading to South Korea to compete against a K-League All-Star team andTottenham Hotspur.