Seven-times Tour de France winner Lance Armstrong has said he is not yet sure if he will ride in next year's race as part of his comeback.

The 37-year-old American, who retired in 2005, announced on Monday he would race in May's Giro d'Italia for the first time.

"There is the possibility that the Giro is the only three-week stage race that I will run. Still today, there are doubts over the Tour," Armstrong was quoted as saying on Gazzetta dello Sport's website (www.gazzetta.it) on Tuesday.

"Everybody knows its importance but the problems I have with the organisers, journalists and fans could be distracting for my mission -- to focus world attention on the battle against cancer."

Cancer survivor Armstrong announced last month that he was returning to the sport partly to promote his global cancer awareness campaign.

He said then that he would race in July's Tour in a bid for an eighth title but he now appears to be having doubts.

"I hope there will be a diplomatic and peaceful solution. Before announcing my return, I contacted organisers but still I have had no reply," he told Gazzetta.

"Is it possible they won't invite me? Everything is possible but I would find it incredible, a sort of own goal. I want to be in Paris but in a calm situation."

Armstrong begins his comeback with the Astana team in January's Tour Down Under in Australia after being allowed to compete by the International Cycling Union (UCI) despite breaching the rules.

Riders making comebacks have to be in the UCI's anti-doping programme for six months prior to racing but the governing body has made an exception for Armstrong, who has always denied allegations of doping.

Armstrong is returning to cycling for at least a year and has not decided if he will prolong the comeback.