Armstrong broke his collarbone during the Vuelta Castilla y Leon in March
Cycling legend Lance Armstrong could face punishment from the French anti-doping agency (AFLD) over claims he violated strict drugs testing rules.
French doctors tested Armstrong's hair, urine and blood in sample taken on 17 March, but found no traces of drugs.
But the medic in charge claimed the multiple Tour de France winner did not "respect the obligation to remain under the direct and permanent observation".
Armstrong denied having "misbehaved" during the random drugs test.
The AFLD said the American behaved strangely when the tester asked him to provide the samples and sent a report to the International Cycling Union (UCI), the sport's governing body.
In a statement, the AFLD says the UCI has given its permission to start disciplinary proceedings against the Texan, although it refused to identify what the possible punishment could be.
"In a letter sent to the Agency on April 8, UCI president Pat McQuaid said an interpretation of the World Anti-Doping code and UCI anti-doping rules confers the AFLD the right to open a disciplinary procedure against Lance Armstrong," said the statement.
"The AFLD is competent to impose disciplinary sanctions to people who do not hold a French licence but train on the national territory."
Any sanctions imposed on Armstrong would only be valid on French territory, so any action could affect his chances of an eighth Tour de France title in July.
The samples were taken following a training ride in the French Riviera town of Beaulieu-sur-Mer.
Armstrong said he was unsure of the identity of the AFLD drug tester who turned up on his doorstep for an unscheduled visit, leading to a 20-minute delay.
Armstrong claimed he was given permission to shower during that period while his assistants confirmed the AFLD official's credentials.
The 37-year-old insisted he did not try to evade or delay the testing process.
"I had never heard of labs or governments doing drug testing and I had no idea who this guy was or whether he was telling the truth," Armstrong said in a statement on Tuesday.
"We asked the tester for evidence of his authority. We looked at his papers but they were far from clear or impressive and we still had significant questions about who he was or for whom he worked.
"I was there with (Astana team manager) Johan Bruyneel and two other people. We told the tester we wanted to check with the UCI to confirm who he was and to make sure he wasn't just some French guy with a backpack and some equipment to take my blood and urine.
I am sorry that they are disappointed that all the tests were negative but I do not use any prohibited drugs or substances
"Johan had confirmed with the UCI that the tester had authority from the French government to take samples. I immediately provided blood, urine and hair samples - all the samples that he requested, as he requested.
"In addition, the form asked the tester to state if there were any irregularities or further observations from the testing process and to that he wrote 'no'.
"I have learned that after the tests were all negative, the laboratory has now suggested that the 20-minute delay should be investigated.
"I find it amazing that I've been tested 24 times without incident and the first test I do in France results in more outrageous allegations and negative leaks to the press.
"I am sorry that they are disappointed that all the tests were negative but I do not use any prohibited drugs or substances."
Armstrong, who came out of retirement in September 2008, recently returned to training following surgery on a broken collarbone sustained during the Vuelta Castilla y Leon in Spain last month.