Iraq has claimed US Apache helicopters attacked a neighbourhood in the central city of Hillah, killing 33 people and injuring more than 300.
US Central Command is investigating the claims, but says no Apaches could have been involved.
Iraqi officials took reporters to the city 55 miles south of Baghdad and showed them bodies of people killed in what they said was a US attack.
One man, Kazem Mohammed, said he was on the road from Nasiriyah, heading to Hillah when the attack happened. He said 11 of his relatives were killed when the vehicle they were riding in was hit.
He said the dead included six of his children, his parents and his wife.