Seven-time winner Lance Armstrong has announced next month’s Tour de France will be his last.‘‘And yes, this will be final Tour de France. It’s been a great ride. Looking forward to three great weeks,’’ the 38-year-old American wrote on his Twitter website. Realising his tweet included several mistakes Armstrong then re-tweeted, ‘‘Doh, sorry, meant ‘‘my’’ final Tour.’’

On Saturday, Armstrong will lead his team RadioShack to begin his bid for an eighth Tour de France title.Monday’s announcement comes just one month after the Texan found himself embroiled in new doping allegations, dismissing accusations levelled by his former teammate Floyd Landis.

Landis, who was stripped of his 2006 Tour de France title after a positive drug test, pointed the finger at numerous cyclists, including Armstrong, and said that doping was intrinsic at the elite level of the sport. Armstrong was quick to attack Landis’ credibility. Armstrong successfully beat cancer in 1998 to go on and win seven consecutive yellow jerseys from the world’s toughest bike race in 1999-2005. He returned to the sport last year after a three-year ’retirement’.

Armstrong placed third at the 2009 Tour race and this year he finished second in the Tour of Switzerland and third in the Tour of Luxembourg. He crashed out of the Tour of California on home soil in May. Armstrong will line up at this year’s race in a team which includes former Tour runner-up Andreas Kloden of Germany, and American Levi Leipheimer among other experienced stage race campaigners.