BAGHDAD, Iraq — A suicide car bomber struck a police checkpoint Wednesday in the Shiite holy city of Najaf, killing at 13 people in the spiritual heartland of the militia factions led by radical cleric Muqtada al-Sadr.
U.S. forces, meanwhile, investigated the "hard landing" of a Black Hawk helicopter north of Baghdad. Military spokesman Maj. Gen. William Caldwell said the airmen were picked up by rescuers, but gave no further details.
At least seven U.S. helicopters have crashed or been forced down by hostile fire in the past month, killing 28 troops and civilians.
Meanwhile, Britain outlined its plan to withdraw around 1,600 troops from Iraq in the coming months and Denmark said it will withdraw its 460-member contingent by August. Lithuania also said it may pull back its 53 troops from the country.
Secretary of State Condoleezza Rice said that despite the announced withdrawals, "the coalition remains intact." In Japan, Vice President Dick Cheney said the U.S. wants to finish its mission in Iraq, then "come home with honor."
Political tremors grew stronger in Iraq following claims that a Sunni woman was raped while in custody of the Shiite-dominated police — a case that threatens to escalate the sectarian friction that drives many of the bombings and attacks across the country.
Prime Minister Nouri al-Maliki fired the head of the influential Sunni Endowment, who had called for an international investigation into the rape allegations.
The Najaf blast hit while streets were filled with morning shoppers. At least seven of the victims were police and the rest civilians, authorities said. It was the first large-scale bombing in months in the city, which is heavily guarded by police and al-Sadr's powerful Mahdi Army militia. More than 40 people were injured.
On Aug. 10, a suicide attack near the Imam Ali mosque killed at least 35 people and wounded more than 100.
Najaf is a major Shiite pilgrim destination for its iconic Imam Ali shrine near the city's huge cemetery — used as a burial place for Shiites throughout the country. It also is headquarters of Shiite spiritual leader Grand Ayatollah Ali al-Sistani and al-Sadr, whose militia engaged in heavy fighting with U.S. forces in the area in 2004.
Government officials marked the first week of a wide-ranging security sweep in Baghdad by U.S. and Iraqi forces seeking to put death squads and insurgents on the run. But a string of bombings in the Baghdad area — which have claimed more than 100 lives since Sunday — have quieted the early fanfare and highlighted the huge challenges of trying to reclaim control of the blood-soaked capital.
A car bomb in the western Baghdad district of Bayya killed at least two and injured 31, police said. Later, a car bomb in the neighborhood killed at least three people. The area, a hotbed of sectarian tensions, is mixed between Sunni and Shiites.
The Iraqi spokesman for the security plan, Brig. Gen. Qassim Moussawi, said the campaign to reclaim control of the city neighborhood by neighborhood "has achieved very important goals despite the expected criminal reactions."
"God willing, the plan will continue to uproot terrorists and outlaws across Baghdad and other areas," he told a news conference. He added that 42 "terrorists" have been killed in the sweeps and more than 250 suspected militants arrested, but gave further details.
Caldwell told a news conference that U.S. and Iraqi forces were focusing on "belts" of extremist activity in Baghdad and suggested political talks are continuing over when and how to move into Sadr City, a stronghold of the Mahdi Army militia.
He added that U.S. military planners are moving ahead with efforts to establish smaller outposts around Iraq. They seek to work with Iraqi soldiers on forging ties with community leaders and gathering sharper intelligence on militants.
"If we are going to protect the population, we have to be down there with the population," he said.
The rape claims by the 20-year-old woman, which surfaced Monday, have sent the political leadership into turmoil.
A statement by al-Maliki's office gave no reason for the dismissal of Ahmed Abdul-Ghafour al-Samaraie, who directed the state agency overseeing Sunni mosques and seminaries. But suspicion fell on his harsh criticism of the government's handling of the rape allegations.
The government's quick rejection of the woman's claims have outraged many Sunnis, who accused al-Maliki of a high-level cover-up. The Association of Muslim Scholars, a militant Sunni group known to have links with insurgent groups, called it a "moral genocide" and warned of more fallout ahead.
"Those who perpetrated this crime must know their guilt will not be forgotten," the group said Tuesday.
A statement by al-Maliki's office accused "certain parties" — presumably Sunni politicians — of inventing the claims to try to undermine forces during the Baghdad security operation.
Caldwell confirmed the woman was treated at a U.S. military hospital, but said no medical reports would be made public because of confidentiality codes.
In London, British Prime Minister Tony Blair said about 1,600 British troops will leave Iraq in the coming months if Iraqi forces can secure the southern part of the country. Britain — the main coalition ally in Iraq — has about 7,100 soldiers in Iraq, concentrated in and around the southern city of Basra
British troops will stay in Iraq until at least 2008 and work to secure the Iran-Iraq border and maintain supply routes to U.S. and coalition troops in central Iraq, Blair told the House of Commons.
"What all of this means is not that Basra is how we want it to be. But it does mean that the next chapter in Basra's history can be written by Iraqis," Blair said.
Denmark said it will withdraw its 460-member contingent from southern Iraq by August and transfer security responsibilities to Iraqi forces. The Danes serve under British command in Basra.
The major effect of the British and Danish withdrawals will likely be political, coming as the U.S. is increasing its troops in an effort to stem violence in Baghdad. Democratic leaders could use the announcements to pressure Bush to put forth his own timetable for U.S. troop withdrawals.
Rice played down the British announcement, saying it is consistent with the U.S. plan to turn over more control to Iraqi forces when possible.
"The British have done what is really the plan for the country as a whole, which is to transfer security responsibility to the Iraqis as the situation permits," Rice said in Germany. "The coalition remains intact and, in fact, the British still have thousands of troops deployed in Iraq."
Elsewhere in Iraq, a U.S. Marine was killed Tuesday in fighting in volatile Anbar province, the military said.
At least 3,149 members of the U.S. military have died since the war began in 2003, according to an Associated Press count.