Nato released video footage of the attack

The stills are taken from video footage transmitted back to the pilot before the bomb struck its target near Leskovac, southern Serbia. They show how the Belgrade-Salonika train came into view in the seconds before the missile hit its target.

Ten people died and a further 16 were injured in the attack which Yugoslavia branded criminal and insane - Nato described it as an unfortunate mistake of war, one for which it apologised.

But General Wesley Clark, Nato's Supreme Commander of forces in Europe said that while the deaths were regrettable, the alliance still had right on its side as it attempted to reverse the ethnic cleansing of Kosovo.

Two missiles were fired in the incident - the first was released from several miles away before the pilot realised what was about to happen.

The second missile was fired at the opposite end of the bridge as the pilot attempted to complete the mission despite hitting the train.

Describing the attack, Gen Clark said that that the pilot had seen a flash of movement - but it had been too late to abort.

"You can see if you were focusing right on your job as a pilot how suddenly that train appeared," said the General. "It was really unfortunate."

Gen Clark said that the pilot, having realised he had missed the bridge, circled and returned to find the other end of the bridge clouded in fire and smoke.

"At the last minute, again in an uncanny accident, the train had slipped forward," said the general.

"So that striking the other end of the bridge he actually caused additional damage to the train.

"We are taking extraordinary measures to avoid collateral damage," he stressed. "We are doing everything we can to follow the minimum use of force."

"We are not going to do a carpet bombing of Belgrade.