BAGHDAD, Iraq - A suicide car bomber struck a police checkpoint near a market Wednesday in the Shiite holy city of Najaf, killing at least eight people and wounding 31, police and hospital officials said.

A man injured in a suicide bomber attack lies in Baghdad's al-Kindi hospital, Iraq, Wednesday, Feb. 21, 2007. A suicide bomber struck a funeral in Baghdad on Tuesday, killing at least seven people and injuring another 15, as militants show increasing defiance to a major security operation in the capital. [AP]

The explosion occurred about 10:30 a.m. as the area in central Najaf, 100 miles south of Baghdad, was filled with shoppers.

On Tuesday, a hidden bomb ripped through a tanker carrying chlorine gas, killing nine people and filling hospital beds with more than 150 wheezing and frightened villagers after noxious plumes covered homes and schools north of Baghdad.

The attack was part of a string of blasts ¡ª including a suicide bomber who killed seven mourners at a funeral ¡ª that further rattled officials marking the first week of a major security crackdown seeking to calm the blood-soaked city. U.S. forces, meanwhile, called in airstrikes during intense clashes against insurgents in strongholds northwest of Baghdad.

With the death toll in the Baghdad area climbing above 100 since Sunday, Prime Minister Nouri al-Maliki tried to court some rare upbeat publicity with an even rarer event ¡ª leaving his heavily guarded quarters for a visit to the city's streets and markets.

The fanfare of the security plan's launch Feb. 14 has been swept aside by a steady roll of attacks, most blamed on Sunni extremists targeting the majority Shiites. Many Sunnis believe they are being sidelined by al-Maliki's government and under growing threat from Shiite militias, which the prime minister refuses to confront.

Meanwhile, British Prime Minister Tony Blair will announce on Wednesday a new timetable for the withdrawal of British troops from Iraq, the BBC reported.

About 1,500 are to return home in several weeks, with a total of about 3,000 British soldiers leaving southern Iraq by the end of 2007, if the security there is sufficient, the British Broadcasting Corp. said Tuesday night, quoting government officials who weren't further identified.

The BBC said Blair was not expected to say when the rest of Britain's forces would leave Iraq. Currently, Britain has about 7,100 soldiers there. Blair's office refused to comment on the BBC report.

The bombing of the tanker took place near Taji, 12 miles northwest of Baghdad. A military spokesman, Brig. Gen. Qassim Moussawi, said a bomb was planted under the tanker, but it was not known whether it had a timer or was remotely detonated. His remarks contradicted earlier reports that a roadside bomb blew up the truck.

Hospitals were soon flooded with terrified people ¡ª including many children ¡ª complaining of breathing problems, vomiting and stinging eyes. Most of the people treated were released after several hours and there was no apparent life-threatening cases, hospital officials said.

Chlorine gas in low exposure irritates the respiratory system, eyes and skin. Higher levels can lead to accumulation of fluid in the lungs and other symptoms, and death is possible with heavy exposure, according to the U.S. Centers for Disease Control and Prevention.

Authorities were left questioning whether the bombing could signal a new tactic by militants to try to spread greater panic with chemical fallout.

The attacks in the capital began during the busy morning rush for goods and fuel.

A car rigged with explosives tore through a line of vehicles at a gas station in the Sadiyah district in southwestern Baghdad. At least six people were killed and 14 wounded, police said. The neighborhood is mixed between Shiites and a Sunni minority.

Later, a suicide attacker drove a bomb-laden car into a vegetable market near a Shiite enclave in southern Baghdad. At least five people were killed and seven injured, police said. The same market in the mostly Sunni Dora district was targeted last month by three car bombs that killed 10 people.

The suicide blast at the funeral came after the mourners filled a tent in a mostly Shiite district of eastern Baghdad. The attacker, wearing a belt packed with explosives, also left 15 people wounded.

Outside Baghdad, U.S. forces pressed attacks against suspected Sunni insurgents.

Helicopter gunships were called in during fierce battles around Ramadi, about 70 miles west of Baghdad, police and witnesses said.

In areas around Buhriz, about 35 miles northeast of Baghdad, U.S. warplanes strafed a neighborhood and leveled a palm tree grove during a daylong battle with Sunni factions firing mortars and rocket-propelled grenades, according to an Associated Press reporter traveling with the unit.

A Humvee was struck with a roadside bomb, killing four Iraqi soldiers. One insurgent fired a rocket, then grabbed a woman and three small children as human shields. Snipers fired down from buildings on U.S. and Iraqi forces.

To the west of the capital, local residents and Iraqi police prevented an al-Qaida convoy from entering the Sunni town of Jumaylah, opening fire on the insurgents and capturing a Syrian who was driving a vehicle rigged with explosives, the U.S. military said.

One Iraqi policeman and a civilian were injured when the explosives-laden vehicle detonated, the military said. The driver survived and was taken to nearby Fallujah, where he was identified as a Syrian, the military said.

Besides the relentless bloodshed, the government struggled with a potentially explosive scandal over allegations by a 20-year-old Sunni that she was raped Sunday by three officers of the Shiite-dominated police.

The government quickly rejected her accusations ¡ª noting that a medical exam did not indicate a sexual assault ¡ª and said the accused should be "rewarded" for having to endure fabricated charges.

Sunni leaders issued sharply worded condemnations and claims of a cover-up.

"We, it would seem, are facing a moral genocide in which government forces play the leading role in addition to their crimes of genocide," said a statement from the Association of Muslim Scholars, a militant Sunni group known to have links with insurgent groups.

"Those who perpetrated this crime must know their guilt will not be forgotten," it said.

A statement by al-Maliki's office accused "certain parties" ¡ª presumably Sunni politicians ¡ª of inventing the claims in an attempt to undermine security forces during the Baghdad security operation.

In a Baghdad courtroom, six officials from Saddam Hussein's regime pleaded innocent of crimes against humanity for a crackdown on Kurds in the 1980s.

The defendants include Saddam's cousin Ali Hassan al-Majid, also known as "Chemical Ali" for allegedly ordering poison gas attacks during the campaign, code-named Operation Anfal, which killed an estimated 100,000 Kurds.

The trial began last year with each defendant rejecting the general allegations. The special tribunal now delivered specific charges to end the investigative phase of the proceedings. If convicted, they could face death sentences.

Saddam was a defendant in the Anfal trial but was sentenced to death after his conviction for the killing of 148 Shiite Muslims after a 1982 assassination attempt. He was hanged Dec. 30.

Meanwhile, a U.S. soldier was killed Tuesday in fighting in western Anbar province and another died Sunday from a non-combat cause. The brief U.S. statements gave no additional details. At least 3,148 members of the U.S. military have died since the Iraq war started in March 2003, according to an Associated Press count.