Four American soldiers were killed in a suicide attack in the central Iraqi town of Najaf on Saturday morning [local time].

The attack took place at a military checkpoint operated by the US Army's 1st Brigade, 3rd Infantry Division.

CNN said there were two attackers, but other reports suggested only one.

The suicide bombing was the first against US and British forces since the invasion of Iraq began.

The Vice-President of Iraq, Taha Yassin Ramadan, warned the US to expect more suicide bombings, BBC reported.

"This is just the beginning. You will hear more pleasant news later," he said at a press conference.

Ramadan identified the bomber as Ali Jaafar al-Noamani, a father of several children.

He said any method that stops the enemy and kills its troops would be used. "What are they doing in our land? Let them pack up and go."