"Leading doctors" are said to be demanding an investigation into what they regard as "subliminal" tobacco advertising on Ferrari's F1 cars and the team's relationship with Philip Morris, manufacturer of Marlboro cigarettes.

The tobacco manufacturers enjoyed a long relationship with F1 that began in 1968, when Player's Gold Leaf brand sponsored the Lotus team, and continued for almost forty years. For much of that time tobacco sponsorship was the lifeblood of the sport with almost all the major teams taking up the habit at some stage.

However, as anti-smoking legislation began to take hold it was inevitable that the sport would need to be weaned off the weed, despite its best efforts.

Ironically, as we look forward to the end of the Labour Party's governance of the British parliament, it was back in 1997, just days after winning the election, that newly-elected Prime Minister Tony Blair was embroiled in a scandal involving tobacco sponsorship of F1. It is claimed that Bernie Ecclestone offered the Labour Party a £1m 'donation' to help fend off a forthcoming ban on tobacco sponsorship of the sport.

While F1 was given a stay of execution, it was inevitable that the sport, like so many others, would have to bow to growing political pressure and by the end of 2006 all but Marlboro - which had signed a new deal with Ferrari in 2005 - had been forced out.

In 2007, Ferrari ran with prominent signage in three races, however, the following year all traces of the Marlboro name were missing from the car, transporters and overall. In their place was a barcode like design which, to most, didn't really mean anything, even though the team still raced as Scuderia Ferrari Marlboro.

Now, with Marlboro's current deal with Ferrari due to end in 2011, leading doctors are said to be "stunned" by what they see as a blatant breech of the tobacco advertising rules.

John Britton, a Fellow of the Royal College of Physicians and director of its tobacco advisory group, said, according to the Times: "The bar code looks like the bottom half of a packet of Marlboro cigarettes. I was stunned when I saw it. This is pushing at the limits. If you look at how the bar code has evolved over the last four years, it looks like creeping branding."

"I think this is advertising," added Gerard Hastings, director of the Centre for Tobacco Control Research. "Why a bar code? What is their explanation?"

Just over a week before the European F1 season kicks off, a spokesman for the European Public Health Commissioner said that the barcode constituted potential subliminal marketing, calling on the Spanish and British governments to investigate as to whether Marlboro is breaking the law.

A spokesman for Ferrari, the car manufacturer which runs the Scuderia Ferrari Marlboro Formula One team, told the Times: "The bar code is part of the livery of the car, it is not part of a subliminal advertising campaign."

When asked about the deal with Philip Morris, he replied: "$100 million (a year) is not a correct figure. We do not disclose the figure, the figure you mention, it is lower."