No charges will be brought against U.S. troops believed to have shot dead ITN journalist Terry Lloyd in Iraq, after prosecutors said it was impossible to prove who fired the fatal shot, the Crown Prosecution Service said on Monday.

Lloyd, one of Britain's most experienced journalists, died after being fired at by Iraqi and U.S. forces near Basra in March 2003.

Forensic evidence suggested Lloyd was first injured by a shot from the Iraqis and then was fatally hit by a bullet from shots fired by the U.S. forces, the CPS said.

The case was referred to prosecutors after coroner Andrew Walker recorded a verdict of unlawful killing at Lloyd's inquest in October 2006.

But the CPS said there was not enough evidence to bring a case against any individual.

"There is also insufficient evidence in relation to the chain of command to establish if there was any person responsible for the chain of events that led to the death of Mr Lloyd," said Sue Hemming, head of the CPS's counter terrorism division.

"I understand that this will be very upsetting news for the family and friends of Mr Lloyd but I can reassure them that every care was taken in pursuing lines of inquiry and reviewing the evidence."

She said the case had been an "extremely complex and difficult investigation".

Lloyd, 50, had been in a two-car convey carrying three ITN colleagues towards Basra after wrongly hearing of the surrender of an Iraqi armoured brigade during the first few days of the U.S.-led invasion.

They were in a war zone and their vehicles were marked "Press", but Lloyd was not wearing his helmet or bullet proof vest.

As the two cars crossed a bridge, Iraqi soldiers drove towards them and opened fire, the CPS said.

The cars did a U-turn to head back towards the U.S. forces, pursued by the Iraqis.

The U.S. Marines believed all the approaching vehicles were hostile and opened fire.

Lloyd, who was lying in the central reservation with a stomach wound, was picked up by a vehicle helping to evacuate wounded Iraqi soldiers and taken to hospital, but on arrival it emerged he had been fatally shot in the head, his inquest had heard.

The driver said shots were fired from the U.S. position.

"It is clear from the forensic evidence that Mr Lloyd received injuries from both Iraqi and American bullets and the forensic evidence suggests that the injury which caused his death was fired from a U.S. weapon," Hemming added.

The investigation into his death has been controversial, with U.S. soldiers declining to attend the inquest in Oxford.

Lloyd's lawyer at the time had demanded that those responsible should be brought to trial for what he termed "a very serious war crime".

The crew's translator, Hussein Othman, was also killed while French cameraman Fred Nerac, is missing believed dead. The other cameraman Daniel Demoustier was the only one to survive.

Lloyd had reported from Iraq, Cambodia, Bosnia and Kosovo during his award-winning career.