The Monegasque driver has dominated Formula 2 this year, with speculation that he will take up a full-time Sauber seat next year.
Leclerc already has four F1 practice appearances to his name from runs with Haas in 2016.
The 2016 GP3 champion currently leads F2 by 59 points and could wrap up that title in the next round of the championship at Jerez (October 6-8).
That clashes with the Japanese Grand Prix at Suzuka, while Leclerc will not drive a Sauber at Abu Dhabi either due to F2 being on the support bill.
Ferrari is keen for both Leclerc and fellow junior driver Antonio Giovinazzi, who raced with Sauber as a stand-in in Australia and China and has completed three of his planned seven Friday practice outings with Haas, to race in F1 next year.
Ferrari president Sergio Marchionne is understood to have recently discussed the possibility of placing both Leclerc and Giovinazzi at Sauber for 2018.
That line-up would have to be at the expense of Sauber's two current race drivers, the Mercedes-backed Pascal Wehrlein and Marcus Ericsson.