Irish Olympic hopes have been severely damaged as three athletes have been injured.
Irish Olympic walker Jamie Costin sustained back and leg injuries when his rented car collided with a petrol tanker in southern Greece.
'There is a big doubt over whether he will compete in the Games', spokesman Jack MacGouran said.
It is understood Mr Costin suffered back injuries, broken toes and a hand injury, but his injuries were not life-threatening. He had been due to compete in the 50-km walk on 27 August.
The 22-year-old had just dropped off his Polish training partner and Olympic champion Robert Korzeniowski following a training session when he was involved in a head-on crash near the town of Porto Heli.
He is being moved to the 'Olympic family' hospital in Athens.
Mr Costin did not finish his event during the 2003 World Championships in Paris after dropping out due to injury and dehydration. In the 2000 Sydney Games, he was the first Irishman to compete in the Olympic 50-km walk since 1968, finishing 38th.
He is the second Irish walker to be ruled out within hours as Ireland's world silver medallist over 20km, Gillian O'Sullivan, had to pull out with a knee injury.
One of Ireland's top hopes for a medal at the Athens Olympics, Ms O'Sullivan was the silver medallist in the women's 20km walk at last year's World Championships and 10th in Sydney four years ago.
Discus thrower Nick Sweeney has also been hurt and may have to withdraw.
