BAGHDAD (Reuters) - Iraq accused al Qaeda ally Abu Musab al-Zarqawi on Monday of carrying out coordinated car bombings on churches that killed at least 11 people, saying the militants wanted to drive Christians out of the country.

In Iraq's growing hostage crisis, militants led by Zarqawi killed a Turkish hostage. In response to the killing and a wave of kidnappings of Turkish drivers, a Turkish truckers' group said it would stop transporting goods to U.S. forces in Iraq.

Top Shi'ite cleric Ayatollah Ali al-Sistani and other Muslim leaders condemned the car bombings, timed for Sunday evening services in Baghdad and the northern city of Mosul. The attacks were the first on the minority Christian community's churches since the start of a 15-month insurgency.

"There is no shadow of a doubt that this bears the blueprint of Zarqawi," said national security adviser Mowaffaq al-Rubaie, adding the militants wanted to spark religious conflict.

"Zarqawi and his extremists are basically trying to drive a wedge between Muslims and Christians in Iraq. It's clear they want to drive Christians out of the country," he told Reuters.

FOREIGN HOSTAGES

Jordanian-born Zarqawi has claimed responsibility for many major car bombings in Iraq since Saddam Hussein was ousted last year and also the killing of several foreign hostages among dozens seized since April.

A little-known Islamist group calling itself the Planning and Follow-Up Organization in Iraq said on a Web site it carried out the bombings, but no independent verification was available.

"You wanted a crusader war, so these are the results ... We warned you," the group said in a statement.

In a video tape of the Turk's execution shown on Islamist Web sites, a masked man shot the hostage while he was seated. When he fell to the ground, the gunman shot him twice more with a pistol while shouting "God is Greatest."

The Turk, dressed in a shirt and trousers, earlier identified himself on the tape as Murat Yuce.

Yuce's wife told CNN Turk television her husband had gone to Iraq to help pay off the family's credit card debts.

"One month's installment was all that remained and then he was going to return ... He would have died for his children and this is effectively what happened," she said.

TRUCKERS' DECISION A BLOW

The Turkish truckers' decision was a blow for Washington and another success for kidnappers who have forced Philippine troops to withdraw and several firms to halt operations in Iraq.

"Until security can be guaranteed we have stopped transporting goods for U.S. forces," said Cahit Soysal, head of the International Transporters' Association, which represents around 30 to 40 companies.

Sunday's car bombs hit at least five churches in Iraq, including four in Baghdad. Police defused two more bombs outside other churches, one in Baghdad and the other in Mosul.

The attacks killed at least 11 people and wounded 55, the U.S. military and police said.

Christians make up three percent of the Iraqi population and have generally had good ties with the Muslim community. Some Christians, fearing growing Islamization in Iraq, have fled to Syria and Jordan.

Human Rights Minister Bakhtiar Amin said the interim government of Prime Minister Iyad Allawi was trying its best to combat guerrillas and uproot their networks.

"NO BORDERS TO BARBARITY"

"This shows there are no borders to the barbarity of the crimes of these terrorists," he said.

Parish priest Bashar Muntihorda, speaking outside a Chaldean church in Baghdad that was hit, said: "The damage that was done is so high to the courage of the people, to their feelings, to their hopes that a bright future is coming."

Volunteers swept up debris, including a broken stained-glass window depicting Christ.

Adding to Iraq's woes is the wave of hostage-taking.

Dubai Television aired video tape of four Jordanian truck drivers taken hostage in Iraq last week appealing to the Jordanian government to help secure their release.

In another hostage standoff, a tribal sheikh is negotiating to secure the release of seven foreign truckers, three Indians, three Kenyans and an Egyptian. The seven were seized last month and threatened with death.

A Somali held by militants linked to Zarqawi would be freed after his Kuwaiti employer agreed to halt operations in the country, Al Jazeera television said.