Forest have been in contact with Saelemaekers' representatives for over a year, even before his loan move to Roma last season.
The 25-year-old attacker spent the 2024/25 campaign on loan at Roma, where he overcame an injury-disrupted start to play 31 games, scoring 7 goals and providing 7 assists.
His versatile attacking abilities have caught the eye of Forest's manager Nuno Espirito Santo, who views Saelemaekers as a potential replacement and cover for Anthony Elanga, the winger currently linked with a move to Newcastle United.
AC Milan are asking for a fee in the region of 25 million euros, while Forest value the player slightly lower at around 20 million euros. This difference remains a key hurdle, but sources suggest it could be bridged depending on negotiations and Allegri's assessment.
Milan's new manager, Massimiliano Allegri, has paused all transfer discussions to evaluate Saelemaekers during pre-season before making a final decision on his future.
Meanwhile, Eintracht Frankfurt has recently emerged as a serious contender for the Belgian's signature.
Newcastle United previously sought information on Saelemaekers earlier this year but did not progress talks, as their interest shifted towards Elanga.