Rahman received cuts on his elbows but was not seriously hurt. His wife, Crystal, sustained cuts and bruises and was fitted for a neck brace before being taken from the scene.

The champion, Crystal and at least two of their three children were sitting in the back of a convertible when it struck a taxicab, hurling the family from the car.

After tending to two children, Rahman walked away from the scene without receiving medical assistance.

The children were taken to The Johns Hopkins Children's Centre and Crystal Rahman to The Johns Hopkins Hospital. A Hopkins spokeswoman said Rahman and his family were not seriously injured. She had no further details.

A witness to the accident, Levern Riley, said there was a police escort with cars in front of and behind the convertible in which the Rahmans were riding. A car ran a red light, Mr Riley claimed, before hitting Rahman's car, which spun around and slammed into a taxi.

Rahman had been honoured as a hero by his hometown city. He had thanked the city saying: "This is Baltimore's day. We all did this together. I remembered Baltimore the whole time I was there."

Mayor Martin O'Malley gave the champ a key to the city. He said: "With a tremendous right cross to the jaw, he showed that Baltimore still has the ability to knock the stuffing out of the British."

Coincidently, the last time Baltimore staged a sports motorcade - for the Baltimore Ravens in January - a police car was hit by the team bus before they left for the Super Bowl.