The Sun says the goalkeeper has been told to return to City for pre-season training on Monday with his future still up in the air.
There was interest from Sporting Lisbon earlier in the summer but a switch to Portugal did not appeal.
Hart knows there is no future for him at the Etihad while Pep Guardiola remains in charge.
New Nice boss Patrick Vieira was linked with Hart last month.
But the strongest interest so far came from Sporting, who finished third in the Portuguese League last term.