The 22-year-old winger scored 17 times and registered 14 assists in the 2021/22 campaign for Leverkusen and has been widely tipped to leave the club in the rapidly approaching summer window.
It emerged on Friday that Newcastle are interested in signing him and he is in fact one of their priority targets for the summer.
Eddie Howe wants more attacking options in his squad and Diaby is a player who Newcastle admire ahead of the transfer window opening.
And it has been claimed that even Leverkusen are ready to do business and sell him in the summer.
Diaby still has three years left on his contract but the German club feel it is the right time to cash in on the winger.
Leverkusen want to raise significant funds from his sale that they are then prepared to reinvest back in their squad.
The Bundesliga outfit are believed to be wanting around £40m from his sale in the upcoming transfer window.
Newcastle would have to get close to breaking their transfer record in order to sign Diaby this summer.