Man shouts 'Cheat!' and 'Liar' at 7-time Tour de Francw winner and RadioShack rider near team bus.

Lance Armstrong was speaking to Tour de France reporters outside his team bus when an angry heckler interrupted him by shouting accusations in French.

Shortly after the end of fourth stage, which was won on Wednesday by Alessandro Petacchi of Italy, Armstrong stepped down from his RadioShack team bus to answer questions.

The man shouted "Cheat!" and "Doper!" at the seven-time Tour winner, who did not respond and climbed into a team car. The man then had a brief argument with Johan Bruyneel, Armstrong's team manager.

The 38-year-old Armstrong, who returned to competition last year following a three-and-a-half-year retirement, has faced doping accusations since his first Tour win in 1999. He has always denied the accusations.