BAGHDAD, Iraq - A car bomb exploded at a police station Saturday near a base in western Iraq used by U.S. Marines, killing 10 Iraqi policemen and wounding 48 other people, officials said.

The explosion hit outside the gates of Marine Camp Al Asad in Baghdadi, 142 miles west of Baghdad. The U.S. military confirmed it was a car bomb and said there were no Americans among the casualties. A hospital official in nearby Haditha said there were at least eight dead and 48 wounded.

The blast came hours after the U.S. military arrested an aide to Jordanian terror mastermind Abu Musab al-Zarqawi and five others during raids on a safe house in the insurgent stronghold of Fallujah, officials said. The aide had risen to prominence in recent weeks as other al-Zarqawi staff had been killed, according to intelligence sources.

The 1:30 a.m. raid in southern Fallujah targeted a site being used as a safe haven by al-Zarqawi's inner circle, according to a military statement.

American forces have stepped up operations in Fallujah in a bid to root out al-Zarqawi's terror group, Tawhid and Jihad, which is believed to operate from there. The group has been blamed in numerous suicide bombings and beheadings of foreign hostages, including recent twin blasts inside Baghdad's Green Zone, which houses the U.S and Iraqi leadership.

Among the most shocking of the kidnappings was that of Margaret Hassan, an aid worker with joint British, Irish and Iraqi citizenship who has spent nearly half her life delivering food and medicine in Iraq. Hassan, who is married to an Iraqi, was seized Tuesday in western Baghdad as she rode to work in her car.

On Friday, Hassan appeared in a wrenching televised statement begging for her life and urging British Prime Minister Tony Blair to withdraw his country's troops from Iraq.

The gaunt, 59-year-old woman's statement puts new political pressure on Blair's government shortly after it agreed to a U.S. request to transfer 850 British soldiers from southern Iraq to the Baghdad area to free American forces for new offensives against insurgents.

"Please help me, please help me," Hassan, who heads CARE International's operations in Iraq, said in a grainy videotape broadcast by Al-Jazeera television. "This might be my last hours. Please help me. Please, the British people, ask Mr. Blair to take the troops out of Iraq, and not to bring them here to Baghdad."

Unlike most previous hostage tapes, this one featured no hooded gunmen, no banners identifying the militant group and no explicit demands for the captive's freedom. Al-Jazeera, the Qatar-based station, said it received the tape Friday but did not say where or how.

On Saturday, CARE International secretary-general Denis Caillaux made an appeal on al-Jazeera to Hassan's kidnappers to release her.

"She is a naturalized Iraqi citizen and always holds the people of Iraq in her heart. CARE joins with many of the people whose lives Mrs. Hassan has touched over her decades of service in Iraq in reaching out to her captors to appeal to their humanity," he said.

Militants have kidnapped at least seven other foreign women over the past six months, and all were released. In September, Italian aid workers Simona Torretta and Simona Pari, both 29, were kidnapped from their Baghdad offices; they were freed three weeks later.

By contrast, at least 33 foreign male hostages have been killed, including three Americans beheaded by their captors. Insurgents, nevertheless, have targeted Iraqi women working for the Americans or their allies, including a deadly ambush Thursday on a bus carrying female airline employees on their way to work at Baghdad airport.

Hassan has done aid work in this country for nearly 30 years. She joined CARE soon after it began operations in Iraq in 1991, managing a staff of 60 Iraqis who run nutrition, health and water programs throughout the country.

Also Saturday, a roadside bomb detonated near a U.S. military patrol along the highway leading to the Baghdad airport, wounding six soldiers, the U.S. military said. None of the wounds were life-threatening.