The Daily Mail says Mikel wants to leave the club at the end of the season.
The Nigeria star, 26, has found first-team opportunities restricted since manager Jose Mourinho's return last summer.
The January arrival of Nemanja Matic, an important addition in a holding role, has further limited Mikel's chances. But he still has three years on his contract and the Blues would demand a hefty fee.
Galatasaray have expressed firm interest but Mikel wants to weigh up his options.
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