Paris - Tour de France champion Chris Froome has blasted anti-doping authorities for failing to test riders at altitude training in Tenerife.
Froome, 28, is one of several Tour contenders who use Tenerife's Mount Teide to help prepare for the gruelling climbs in July's race.
But the Team Sky rider said he was stunned not to have been tested there during a two-week training camp that ended Wednesday.
"Three major TDF contenders staying on Mt Teide and no out-of-competition tests for the past two weeks. Very disappointing," said Froome on Twitter.
He added that he was not hoping to catch out his rivals - Italian Vincenzo Nibali and Alberto Contador of Spain -- but rather to demonstrate the validity of his efforts and those of his main competition.
"To clarify I am one of those three and I think it's in all our best interests to be able to prove we are clean no matter where we train," he added.
The Briton later told Cyclingnews.com he had asked other teams "but none of them, from what I could gather, had been tested either."
"Alberto, Vincenzo, we're all up here with our respective teams and at the end of the day we're the ones that have to stand in front of the television cameras in July and justify performances.
"All three of us are GC (overall) contenders and the probability is that whoever is in the yellow jersey in July is going to have to answer questions and if we're not getting tested that doesn't look good on any of us."
The Tour is just over a month away and potential winners are in a crucial phase of their training. If they were to take illegal substances to improve their condition in the run-up, now would be a logical time to do so.
This is why Froome thinks it is so important to test riders at this time, to help them prove their innocence.
"We're doing everything we can to show that cycling has turned a page and it's not like it was in the past, but things like this don't help," he added.
"I know from last year, journalists do ask whether we've been tested while we've been up here and we can only say we weren't. That's not good for the image of the sport or piece of mind.
"It would be good to have more testing done up here, especially this close to the Tour de France. This period of training is a building block for the Tour, before the Dauphine and I would have expected to see more testing and it's disappointing."
Nibali weighed into the debate by claiming he had been tested five times this season, although he admitted not while in Tenerife.
"Some may have misinterpreted my tweet thinking that I was trying to turn on the other contenders up here, but that is not the case," clarified Froome.
"I think that if we're trying to show that the sport has changed it's difficult to do so if we're not being tested up here."