An al-Qaeda linked group has claimed responsibility for a suicide truck bomb that killed nine US soldiers and wounded 20 today, in one of the worst attacks on US ground forces since the invasion in 2003.
"Two knights from the Islamic State in Iraq ... driving two booby-trapped trucks hit the heart of the Crusader American headquarters in the region of Diyala," a statement from the self-styled militant group said in a Web posting.
The U.S. military said only one suicide attacker was involved in Monday's strike on a military outpost at Diyala, north of Baghdad, scene of fierce fighting between American troops and Sunni Arab insurgents and al Qaeda militants.
Two witnesses said the outpost was located in an old school in the village of al-Mukhisa.
One said an initial suicide truck bomb exploded inside the yard after ramming through barricades. Another suicide truck bomb followed shortly after, he said.
"The building collapsed ... There was a huge fire," said the witness, who declined to be identified.
The second witness said the explosions were followed by a raging gunbattle.
Near the city of Ramadi in western Anbar province, a suicide truck bomb killed 25 people and wounded 44, police said. They said the attack targeted police and civilians.
The attack took place near a makeshift football field and market in the Albufarraj area east of Ramadi as a police patrol passed by. Police, women and children were among the dead, police said.
Ramadi, 110 km west of Baghdad, is the capital of the volatile Anbar province, a bastion of the Sunni Arab insurgency. Militants from Sunni al-Qaeda and local Sunni tribes are engaged in a bitter power struggle in Anbar.
On Monday, three suicide car bombers killed 20 people and wounded 35 others in Ramadi.
Witnesses have said there is a heavy police presence in Ramadi after police had received information that car bombs and suicide bomb vests were in the area.
While frontal assaults by insurgents against heavily fortified US bases in Iraq are rare, a two-month-old security plan that places troops in less protected garrisons in Baghdad and neighbouring areas has exposed them to greater risk.
In an interview to an Egyptian television station broadcast in Iraq on Tuesday, Prime Minister Nuri al-Maliki said Iraq had become the "most prominent arena in the fight against al-Qaeda".