The Italian forward, who has been capped four times by the Azzurri, is understood to have grown unsettled with the Belgian giants, who finished as runners-up in the Jupiler League last term.
And reports claim that this has alerted Sunderland, who are still searching for their first signing of the summer.
The Black Cats are now managed by David Moyes, who replaced Sam Allardyce following his move to succeed Roy Hodgson as England boss in a saga that has somewhat derailed the North East club’s preparations for the coming season.
Okaka, a powerful striker, netted 13 goals in 27 appearances for Anderlecht, but his future has been thrown into doubt of late amid claims the club have deemed him to be overweight following his return from a summer break.
Sunderland are currently short of options up front, with Jermain Defoe injured.