A US helicopter has come down in southern Iraq after apparently coming under heavy fire from insurgents, according to reports by witnesses.

They said the helicopter came under attack near Latifiya, 40km (25 miles) south of the capital, Baghdad.

The US military confirmed a helicopter had gone down with four people injured. But it did not specify the cause.

The US has lost more than 50 military helicopters in Iraq since the invasion with the loss of a number of soldiers.

A major security operation in Baghdad has resulted in a decrease in the number of attacks on coalition troops there, the US military says.

However, the deaths of eight coalition soldiers were announced on Thursday - four British and four American.