Michael Phelps told police that he drank a beer about an hour and 15 minutes before he was involved in an accident last week, but alcohol wasn't the reason for the incident, according to a police source.

On Thursday, Phelps was driving a Cadillac Escalade when it collided with a Honda Accord driven by a Maryland woman. The athlete showed no signs of alcohol impairment, and was not given a field sobriety test.

"No alcohol was involved. No drugs," a police source said. "It was just a car accident."

Investigators found that the Accord's driver, Amanda E. Virkus, was at fault for the crash. She will be cited for failure to obey a red light, and for causing an accident.

Phelps will be cited for driving with an invalid, out-of-state license. When police arrived on scene following the mishap, the Olympic swimmer presented an invalid Michigan drivers license. According to a police source, the Michigan license was no good because Phelps did not pay an earlier fine for not showing proof of insurance. "It looks like he didn't pay a reinstatement fee, and the license was suspended," the source said.

Phelps will have to appear in court to explain why he was driving without a valid license. In 2004, Phelps pleaded guilty to driving while impaired. He was sentenced to 18 months' probation.

The 24-year-old swimmer, who holds the Olympic record with 14 gold medals for swimming, wrote on his Facebook page that he is nursing a sore ankle stemming from the Thursday crash, but that he plans to train as scheduled on Monday.