SPA-FRANCORCHAMPS, Belgium -- Lewis Hamilton doubts title rival Sebastian Vettel would accept the challenge of racing alongside him at Mercedes in 2018.

Though Kimi Raikkonen has been retained for another season at Ferrari, championship leader Vettel appears to be no closer to signing an extension with the Italian team beyond 2017. Recent reports in Italy claim the German is reluctant to sign a new deal while there is a possibility to sign for Mercedes, with the world champions yet to confirm whether Valtteri Bottas will remain beyond this season.

Hamilton, whose contract runs until the end of 2018, trails the Ferrari driver by 14 points in the title fight but does not think it will become an in-house fight next year.

"I think it's highly unlikely that he would be here," Hamilton said about the prospect of being joined by Vettel. "I don't think he wants to be my teammate... I'm always game to race whoever it is and racing against the best drivers is always a great thing."

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When asked to clarify why he doubted Vettel would want to compete in equal machinery, Hamilton made reference to the fact Ferrari appears to be favouring the four-time world champion over Raikkonen in this year's title fight.

"I'm stating the obvious, but I know he doesn't want to be my teammate. He wouldn't be in the position he is in now in terms of how the team operates if he was here."

Hamilton has been pleased with the addition of Bottas this season, with the Finn proving to be a fast and reliable replacement for the retired Nico Rosberg. In contrast to Ferrari, Mercedes is refusing to throw its full support behind one driver, a mindset best highlighted by the decision to reverse a mid-race swap between Hamilton and Bottas at the Hungarian Grand Prix when the three-time world champion was unable to catch and pass Raikkonen.

With Mercedes clearly a more harmonious place than during the fractured and tense days of Hamilton and Rosberg fighting for the title alone, Hamilton sees little reason the team would change its current line-up.

"I think the team is in a very very good [place]... the last race is actually one of the best examples of how great the team is currently. Coming into this season I haven't changed a single thing that I do but there is a new element in the team and it works. So I don't believe any of the bosses or any individual at the team is unhappy with what is currently in place, so I find it unlikely they would change that."