McLaren's partnership with engine-supplier Mercedes-Benz - believed to have been on rocky ground for some time - could culminate in divorce as soon as the end of the 2009 F1 World Championship campaign, it has been rumoured, with reports that BMW is set to fill the breach.

A number of factors are understood to have led to the apparent deterioration of the McLaren-Mercedes relationship, which since its foundation back in 1995 has yielded no fewer than four world championships (three drivers' crowns and one constructors' trophy) and 60 grand prix victories. Of late, however, the strength of the ultra-successful partnership has been assaulted by a number of scandals - from the 2007 'Spygate' row to reigning F1 World Champion Lewis Hamilton controversially being caught lying to race stewards following the Australian Grand Prix in Melbourne this year.

That is believed to have left a bad taste in the mouth at Mercedes, and allied to the poor early-season performance of the aerodynamically ill-born MP4-24 - despite the Stuttgart manufacturer's engine widely-acknowledged to be the best on the starting grid - and contrastingly excellent form of Brawn GP, which the three-pointed star helped to save from extinction last winter, there has been increasing speculation in recent months that Mercedes is looking to switch its allegiance and acquire a shareholding in the ex-Honda F1 outfit instead.

To that end, whilst initially pushing for McLaren to snap up highly-rated Williams star Nico Rosberg for next year, it is now understood that the young German is more likely to end up at Brawn as team-mate to world champion-elect Jenson Button - another indication that Mercedes' priorities may be shifting.

Should a split indeed occur, it has been reported by German magazine Auto Motor und Sport that McLaren is in discussions with BMW about purchasing the Bavarian marque's engine division - not part of the Qadbak Sauber deal - once the company officially withdraws from top flight competition at season's end.

The move would transform the Woking-based concern back into an independent operation once more in the truest sense of the word - charged with building both its own chassis and engine, one step further towards its purported goal of becoming a 'British Ferrari' - and according to the report, it is former team principal and McLaren Group chairman Ron Dennis who is behind the plan.

BMW is said to be willing to sell - at the right price - and McLaren is believed to have been promised backing for the initiative by way of increased input from its Bahraini investors. The only sticking point is the two years remaining on the current Mercedes contract - but team principal Martin Whitmarsh has dismissed the stories.

"We have no plans to buy BMW's engines," the Englishman asserted, as a McLaren spokesman described the rumours as 'complete nonsense'.

Aside from the cooling in relations in terms of the F1 project, Mercedes elected to design its SLR replacement the SLS AMG Gullwing in-house, whilst McLaren are similarly going it alone in the conception of the new MP4-12C road-going supercar.