UPDATE: Ducati has now confirmed Casey Stoner's return as a 'brand ambassador and test rider' - see separate story...
Retired MotoGP champion Casey Stoner will end his five year collaboration with Honda at the end of this year - paving the way for a rumoured return to Ducati.
The Australian moved to Honda from Ducati in 2011, where he claimed a second MotoGP crown before leaving the sport at the end of 2012.
Stoner has since taken part in MotoGP test riding duties for the Japanese factory, plus an entry in this year's Suzuka 8 Hours, where he was injured after the throttle stuck open.
Earlier this year the 30-year-old offered to fill-in for injured former team-mate Dani Pedrosa, but was surprisingly turned down by HRC.
Upon announcing Stoner's departure, HRC vice president Shuhei Nakamoto said: "We have great memories of Casey's time with Honda. From the moment he arrived in 2011 in the Repsol Honda Team we had a very close relationship and we always enjoyed speaking to him about racing and technical matters.
"Of course his Championship win in 2011 was a very special moment for us and a highlight of my career. Even after his racing days were over, I enjoyed attending his tests to take with him and spend time together.
"We would like to thank him for everything he gave to us over the past five years and send our best wishes to him and his family."
Rumours of Stoner's shock return to Ducati as a test rider - but with the potential for some wild-card races - have been gathering momentum in recent weeks.
At the Valencia season finale, Ducati Corse Sporting Director Paolo Ciabatti declared:
“As you know Casey has been a hero for Ducati, winning many GP races and the world title in 2007. Obviously he moved to Honda and has been working with them, but still he is in the heart of all the Ducati fans and has a good relationship with many Ducati people.
“So let's see what the future brings. We know the contract with Honda expires at the end of this year and obviously if there is a chance to do something together we would love to do it. That is the only thing I can say.”
Ducati hasn't won a MotoGP race since Stoner's exit at the end of 2010, despite signing Valentino Rossi for the 2011 and 2012 seasons.