Lance Armstrong says he would still be issuing strident denials if he hadn't been caught and then forced to admit to using performance-enhancing drugs to win the Tour de France.

"If this stuff hadn't taken place with the federal investigation, I'd probably still be saying 'no' with the same conviction and tone as before. But that gig is up," Armstrong said in an interview with US news broadcaster CNN.

For more than a decade, the disgraced American cyclist Armstrong repeatedly denied he ever used banned drugs and bullied others who accused him of being a cheater.

Armstrong was stripped of his seven Tour de France titles in 2013 for doping and handed a life ban from the sport, eventually admitting that all seven triumphs were fuelled by banned drugs.

Armstrong admitted to doping during a television interview broadcast in January 2013 with American talk show host Oprah Winfrey.

The Texan admitted to using substances like EPO, human-growth hormone and testosterone and other drugs during the many years he dominated international cycling.

"No one forced me or bullied me, so I am not going to say 'It's not my fault' I blame myself, that's the bottom line," he said.

The 42-year-old Armstrong told CNN that his "day-to-day life is positive".

"I never get crap, not once, and I'm surprised by that. Sure, I sometimes get the vibe that someone wants to say something, but it's never happened," he said.

Armstrong has granted several interviews of late but he denied it is part of a carefully orchestrated public relations campaign to try and rebuild his tattered image.

"I know at times it looks like it, but there's no PR campaign," he says. "There's not a big study room where we're bouncing off ideas saying, 'Let's do Esquire, let's talk to (CNN).' I'm just flying by the seat of my pants."

He added he plans to write a third book that "needs to be pretty intense and transparent"

"I need to write a book and it needs to be pretty raw," says Armstrong. "The book needs to be pretty intense and transparent. I need to 'boom' -- put it out there and let it sit.

"The sooner the better. It has to be the right book, the right tone and there has to be totally no bullshit."