“It’s a huge mistake, which I regret deeply.”
Police described the collision as a drink driving incident causing tens of thousands of francs worth of damage, but did not identify Ullrich as the driver at fault.
“I was stressed, coming from an appointment, and wanted to go home as soon as possible.”
He initially told the paper no alcohol was involved.
Police added the accident was caused by the driver not braking in time.
Ullrich’s accident is the latest chapter in a story of an athlete whose successful career was tarnished by doping offences.
He went on to capture gold and silver medals in the Sydney 2000 Olympics after winning the Tour de France in 1997.
But in 2006 he was barred from the classic French race amid doping speculation and he retired the following year.
The Lausanne-based Court of Arbitration for Sport found him guilty in 2012 of a doping offence and he was stripped of all results obtained since 2005.
Last year, Ullrich admitted to blood doping with the help of Spanish doctor Euefemiano Fuentes.
This week's accident is not the first time the cyclist has been implicated in a motor vehicle accident.
In 2002, his driver's licence was suspended after he was caught drink driving in Germany, crashing his Porsche into a bike rack.
The three cars involved in the accident were write-offs. Photo: Thurgau cantonal police