Iraqi security and hospital sources said at least seven Iraqis were killed and 30 others injured in Thursday's attack in Tal Afar.
Bashar Sameer, an Iraqi journalist, told Aljazeera the bomber was a woman wearing a belt of explosives that she set off at 9am (0600 GMT) on Wednesday in front an Iraqi army recruitment centre in Tal Afar, a mixed city 150km east of the Syrian border and 420km northwest of Baghdad.Abu Musab al-Zarqawi's group claimed responsibility in an internet statement.
The statement, whose authenticity could not be confirmed, was signed by one of al-Zarqawi's groups, al-Qaida Organisation in Ard al-Rafidain (al-Qaida in Mesopotamia - the ancient name of Iraq which in Latin means the Land of Two Rivers).
The same centre was recently the target of another attack, Sameer added.
Agencies quoted police Brigadier Saeed Ahmed al-Jibori as saying the attacker set off the charges while standing among job applicants in Tal Afar.
Iraqi police recruits have been
the target of deadly attacks
On 8-12 September, US-led forces routed fighters from Tal Afar in a major offensive, killing nearly 200 suspected fighters and capturing 315, Iraq's military said.
That prompted Jordanian-born al-Zarqawi to declare all-out war on Iraq's Shia community.
Later, al-Zarqawi issued a qualifier, exempting certain groups, including followers of Muqtada al-Sadr, the Shia cleric based in Najaf.
A bomb exploded at the house of a bodyguard of cleric al-Sadr in the southern Iraqi city of Najaf on Wednesday, killing at least six people, an aide to Sadr said.
The blast shattered the relative calm enjoyed in Najaf and threatened to antagonise the fiery cleric's militiamen, who have largely refrained from violence since they fought US troops in the sacred Shia city in November.
Unrest in the Shia south would pile pressure on the government, which is facing fierce revolt in central Iraq.
Sahib al-Amiree, a spokesman for Sadr, accused "foreign elements" of carrying out the Najaf bombing. He said it killed six people and wounded eight at the home of the bodyguard, Kassim al-Mansouri, who was not present.
Al-Sadr's Mahdi Army militiamen recently clashed with the Iranian-trained Badr Brigade movement, which is linked to one of the Shia parties leading Iraq's US-backed government.
The young cleric has proven his ability to mobilise thousands of fighters and complicate Iraq's security crisis.
Iraq's government faces almost daily bombings and the violence shows no signs of easing.
An Iraqi police officer and a civilian were killed when they were caught in gunfire against a Jordanian embassy car in Baghdad on Wednesday, a government official said.
"A Jordanian embassy car came under fire in Baghdad this morning when terrorists opened fire on the vehicle," the official said in a statement carried by the state-run Petra news agency.
None of the car's passengers was hurt, but the driver of a civilian car and an Iraqi police officer behind the Jordanian diplomatic car were killed.
Amman has withheld plans to raise its diplomatic representation in Iraq, which is run by a charge d'affaires, amid security concerns in the violence-ridden country where several diplomats have been the targeted.
Earlier this month, Deputy Prime Minister Marwan Moasher said Jordan would not reveal when its new ambassador to Iraq, Ahmad Lawzi, would take up his duties.
Four US servicemen were killed in Iraq, the US military said on Wednesday.
There has been no let up in
attacks on US soldiers in Iraq
A soldier and an airman were killed by a roadside bomb near Safwan, not far from Iraq's border with Kuwait, the military said in a statement. Another soldier was also injured in the blast.
In the western city of Ramadi, a soldier assigned to the 2nd Marine Division, II Marine Expeditionary Force was killed on Tuesday by gunfire during combat operations.
The US military also announced on Wednesday that a Marine
from the 2nd Marine Division, II Marine Expeditionary Force
died from a non-hostile gunshot wound two days earlier at a
base near Falluja.
The deaths brought to 1922 the number of US service
members who have died since the Iraq war started in March
2003, according to an Associated Press count.
Another five civilian Defence Department employees have also been killed, according to Pentagon figures.
In Baquba, east of Baghdad, a car bomber killed a civilian and wounded 13 people at a police checkpoint on Wednesday, police said. Eight of those wounded were police officers.
The killing comes just a day after a bomber attacked a police recruitment centre in the same town, some 60km north of the capital, killing 10 people.
In another development, police arrested four people in connection with the murder of five Iraqi teachers and their driver at a school south of the capital, a senior officer said on Wednesday.
"We arrested four men accused of murdering the five teachers," said Lieutenant-Colonel Yass Khudairi, the police chief in Mahawil, some 20km north of Muwalha where the primary school is located.
Khudairi said the suspects were captured early on Wednesday in an operation launched on Tuesday night.
"We have obtained their confessions, and they provided us with intelligence on 10 other suspects," he said, adding that a search was under way.
Among those arrested was Qais Mahmud al-Janabi, alleged ringleader of the group, said to be linked to Tawhid wal Jihad of al-Zarqawi, al-Qaida's top operative in Iraq.
On Monday, 10 masked men allegedly entered the school and dragged the teachers - all of them Shia - from their classrooms, took them to an empty classroom along with the driver and shot them, police said.