Real Madrid -- the club widely thought to be leading the chase for the most potent forward in world football -- are among a number of other clubs to have expressed an interest, the source said.
Al Hilal have made a formal offer by letter, the source said, but such a transfer could only be made with the agreement of Mbappe who has never expressed an interest in moving to the fast-growing Saudi league. "The club has given permission to Al Hilal to speak with Mbappe.
That's the request of the letter and that's been granted," the PSG source said. Riyadh-based Al Hilal are one of the handful of clubs owned by Saudi Arabia's Public Investment Fund (PIF).
Read more Will he stay or will he go? Mbappe's future at Paris Saint-Germain in doubt They have already signed central defender Kalidou Koulibaly from Chelsea and Ruben Neves from Wolves this summer.