Chris Froome retains the Tour de France yellow jersey despite Rafal Majka

Such a gap at this stage has not been seen since 2006 and the speculation that Froome could be doping grew on Wednesday with the release of a second video apparently containing leaked, confidential performance data from the 30-year-old rider. Zakkari Dempster of the Bora-Argon 18 team after he rode in too slowly on the stage to be allowed to continue.

Froome starts Thursday’s stage a long way out in front.

“I understand people’s reactions”, Armstrong said.

“There would be some interesting things that come out of it and maybe as a team we might even learn something from it. But at the moment I’m focused on the race”.

However, Armstrong declined to be drawn on Froome and the numerous questions about doping issues that were levelled at him.

Armstrong played coy on Twitter, however, earlier this week when it came to questions about current Tour leader Chris Froome, whose commanding lead has some critics asking whether he’s been doping.

“[But Armstrong] is not on the line with us here, we’re not going to see him, it’s a non-event for us”.

A Sky spokesman said by e-mail: “Our zero tolerance policy is well-known and well-established – nowhere more so than within our own staff who have all been interviewed extensively about their careers before joining the team”. “How can I answer that question?” he replied. “If that were the rule, the caravan would nearly be empty”, Armstrong said.

There have been suggestions Team Sky are using controversial, but legal, ketones, which are said to have benefits for endurance athletes, such as by preserving energy stores and muscle while burning fat.

He added: “I’m focused on my race, I’m focused on my rivals, my team-mates, actually how things are out on the road”.

The stage victory by Majka, a Pole who won twice on last years Tour, provided a lift for a Tinkoff Saxo Bank team whose leader, two-time Tour victor Alberto Contador, has been struggling in this years race. He had begun the 117-mile stage from Pau to Cauterets more than 44 1/2 minutes behind.

It was the Katusha rider’s second victory on the Tour following his stage three win at the Mur de Huy in Belgium.

Richie Porte was Australia’s highest finisher in the stage, coming in 29th at 12:38, while Michael Rogers remains the highest placed Australian in the overall standings, in 25th position.

It left Tejay Van Garderen, safely home in 13th, second at 2min 52sec overall with Quintana third at 3min 09sec.

Contador, attempting a rare Giro d’Italia/Tour de France double, lies sixth, 4:04 off the pace.

But 2014 champion Vincenzo Nibali slipped further behind and is now 7:47 adrift of Froome.

Many race observers say Froome has been so dominant that it looks unlikely that he will lose the three-week race when it finishes on Paris’ Champs-Elysees on July 26.

It was a mountain-filled agenda which took the peloton over 195 km from Lannemezan to the Plateau de Beille in the Pyrenees.