That is the claim of the French TF1 television commentator Jean-Louis Moncet, writing in his Auto Plus column.
It emerged recently that McLaren has offered the 2008 world champion - whose current contract runs out this year - over $30 million a season to stay at the British team for five more years.
But Moncet said "one of my best sources" is reporting that Briton Hamilton has effectively already decided to leave McLaren at the end of 2012 "and even earlier if the situation does not improve".
British newspapers reported after Monaco that Hamilton was angry at the end of last weekend, the 27-year-old insisting "the team definitely have some work to do" to cut out errors and return to the pace.
Moncet said there has been "serious contact between McLaren and Paul di Resta", the rising Force India driver who ironically is managed by Hamilton's father Anthony.
Referring to the speculation surrounding Hamilton at present, former driver, driver manager and respected British commentator Martin Brundle noted: "He's comfortable at McLaren.
"But will he fancy a bit of fresh oxygen by going somewhere else?" he wondered to Sky Sports. "I imagine he's weighing that all up at the moment."