BAGHDAD — A car bomb detonated in the middle of a busy market in central Baghdad today, killing at least 11 people and wounding 64, police and hospital officials said.

At least one woman and a child were killed in the blast, a police officer said on condition of anonymity as he was not authorized to talk to the press.

The popular market in Tayaran Square — a predominantly Shiite area that has been targeted by insurgents in the past — was full of shoppers heading home from Friday prayers. In late May, a car bomb killed 23 people in the square.

The bombing comes at the end of a relatively quiet holiday period in Iraq's capital.

Violence across the country is down nearly 60 percent, according to the U.S. military, largely because of an influx of American troops in the capital and the growth of anti-al-Qaida in Iraq groups in Anbar province and elsewhere.

But violence still plagues Diyala province just north of Baghdad, where U.S. commanders say many of the militants that held parts of the capital earlier this year have fled.

American and Iraqi troops have increased operations in Diyala in recent weeks.

The U.S. military said it had killed four heavily armed gunmen tied to al-Qaida in Iraq in an operation today near Muqdadiyah in Diyala. Another was killed in a predominantly Sunni area south of Baghdad.

On Thursday, the U.S. military said that it had killed 12 suspected terrorists and detained 37 others during a Dec. 22-25 operation near Muqdadiyah.

In Seoul, South Korea's parliament voted today to extend the country's troop deployment in Iraq for another year, amid protests by activists opposed to the decision. South Korea has 650 troops in Iraq.

Meanwhile, an official with Iraq's oil ministry said late Thursday it had threatened to stop all crude exports to South Korea if Seoul proceeds with a deal it signed with the semiautonomous Kurdistan regional government.

The comment backs up the central government's promise to not do business with oil firms trying to get a foothold in Kurdistan before a new oil revenue-sharing law is passed.

In early November, a consortium led by the state-run Korea National Oil Corp., or KNOC, secured exploration rights from the Kurdish regional government for an oil field in the northern province. The Korean consortium includes SK Energy, South Korea's biggest oil refiner, and GS Holdings Corp.

"The ministry has made it clear that no contracts should be signed until a new national oil law is passed," Assem Jiham, a ministry spokesman, told The Associated Press. "There was a clear warning to these companies that they will be blacklisted and excluded from any future cooperation with the ministry."

He added there would be "no leniency" shown to any company that signs such contracts.

According to KNOC, South Korea had imported 42 million barrels of oil from Iraq through November, nearly triple all its imports from the country last year.