Red Bull team principal Christian Horner does not believe a move for Lewis Hamilton would suit his team.
McLaren's Hamilton, 26, has been linked with a switch to Red Bull in the build-up to Sunday's British Grand Prix.
But Horner finds it "difficult to envisage" Hamilton and Red Bull's world champion Sebastian Vettel would work as a partnership.
"History dictates that two world-class drivers in the same team has not always been the best pairing," said Horner.
"You only have to think of Senna-Prost, Piquet-Mansell, or even Alonso and Hamilton.
"We are hugely happy to have Sebastian committed to the team long term, and with Mark [Webber], we're very pleased with the job he is doing.
"Our focus at present is on those two drivers rather than looking to change anything."
Speculation over Hamilton's future intensified after he was seen meeting Horner in the paddock following qualifying for June's Canadian Grand Prix.
Suggestions that the 2008 world champion has a release clause in his McLaren contract that could result in him leaving at the end of the 2011 season has further fuelled talk of a move.
But Horner was keen to pour cold water on any idea of Red Bull signing fellow Englishman Hamilton.
"I think it would be difficult to envisage a driver of Sebastian's calibre and that of Lewis under the same roof," Horner added.
"Lewis is a wonderful driver and you can understand why he might want to drive a Red Bull. It's obvious.
"But would it be the best thing for us? We have severe reservations it would be."
Speaking ahead of Sunday's race at Silverstone, Hamilton was keen to distance himself from speculation that he could leave the Woking-based team.
"I don't read the papers and I don't read the stories. I don't let any outside negativity affect my preparation," Hamilton told BBC Sport.
"The most important thing is focusing on the season. It's far, far too early to be thinking of anything else.
"I don't have any plans on the future and I am pretty comfortable in my contract."
McLaren managing director Jonathan Neale was equally keen to reject reports of Hamilton's possible departure.
"I don't want to be unduly sceptical or dismissive of the press but we are entering the silly season for drivers and there has been a lot of speculation about it," Neale told BBC Sport.
"We would very much like Lewis to stay here. He is a fantastic competitor and we love working with him.
"He has also said that he wants to stay and I am very hopeful that that's the way it washes out."
Despite Red Bull heading to the British Grand Prix 89 points ahead of McLaren in the constructors' championship, and Vettel leading the drivers' championship by 77 points after winning six of the first eight races of the season, Neale is positive about his team's chances going into Silverstone.
"The guys should be optimistic because I think we've got some great upgrades this weekend," he added.
"I'm not in any way disheartened or dispirited by our ability to be competitive.
"We are really looking forward to Silverstone - a high-speed circuit, two British world champions and it feels like a home grand prix. There's a huge amount of excitement. "