Millar is on a quest to rebuild his career as a clean athlete

The already troubled sport has been rocked by a spate of recent doping confessions, while investigations are on-going into a host of leading riders.

"Cycling is a complete mess at the moment and it's been building up for years," said Millar, who has himself served a two-year ban for doping.

"It's going to get worse before it gets better."

Interview: Cyclist David Millar

Millar admitted taking the banned blood-boosting drug erythropoietin (EPO) in 2004 but goes into this year's Tour de France, which starts in London on Saturday, as a reformed character and ardent anti-drugs campaigner.

We all had our heads in the sand David Millar

But the 30-year-old Scot, who now rides for the Saunier team, is swimming against the tide, given the rash of recent revelations.

Last year's Tour de France winner Floyd Landis is currently awaiting the verdict of a doping hearing, while Giro D'Italia winner Danilo di Luca is also being investigated.

In addition, 2006 Giro winner Ivan Basso was recently handed a two-year ban and 1996 Tour de France winner Bjarne Riis admitted using performance-enhancing drugs, as did former Telekom team-mates, Eric Zabel, Udo Boelts, Bert Dietz, Christian Henn and Rolf Aldag.

Bjarne Riis, the 1996 Tour "winner", has admitted to doping

Millar added: "It was 40 years ago that [British rider] Tommy Simpson died due to doping and it's only now we're facing the realities of the problems we have in our sport.

"We all had our heads in the sand. But the public looking at our sport and saying it's a mess will help us because we have to deal with it.

"Before, a lot of the riders and the majority of team management and even governing bodies turned a blind eye. Now they are having to face it.

"UK Sport have got probably the most advanced anti-doping programme in place but different nations deal with their athletes in different ways.

I want to win another stage - I'm coming into the Tour strong enough to perform David Millar

"We need international laws, but that's going to take time and, unfortunately, our sport is a case study of what not to do.

"Part of my penance in a way was to talk about doping in sport and what I went through. It's irresponsible if you've been through something like this not to try to make a difference."

Millar won the opening prologue in his first Tour seven years ago and narrowly lost it in 2003 when his chain came off with just metres to go.

He went on to win a stage in B�ziers the same year before being convicted of doping offences before the 2004 Tour.

Millar (left) and Wiggins will fight it out in Saturday's prologue

On his return, he finished 59th in last year's Tour and won a time-trial in the Tour of Spain last September, as well as the Paris-Nice prologue this spring.

Now Millar, along with Olympic pursuit champion Bradley Wiggins, is one of the favourites for Saturday's prologue around the streets of London and has been training specifically for the 7.9km time trial.

"Saturday is massive, but whether I win it or not I want to win another stage - I'm coming into the Tour strong enough to perform," said Millar.

"Bradley has raised his game a lot this year and he, Fabian Cancellara, Dave Zabriskie and George Hincapie wouldn't be surprise winners."

As a time-trial specialist, Millar is not likely to be a contender for overall victory, but he has tipped Kazakh rider Alexandre Vinokourov and German Andreas Kloden, who both ride for Astana, as "the men to beat".

"Kloden has a proven track record and "Vino" tends to achieve his goals and they've both got a very strong team around them," Millar said.

"However, Kloden's riding for a Kazhakstan team and I'm sure the law will be laid down because Vino is one of their national heroes.

"But they're both good sportsmen and I'm sure they'll let each other race their race.

"But Carlos Sastre is somebody I'd love to see on the podium, or even win it.