In Baghdad, four battalions of Iraqi troops and three battalions of police backed by US forces cordoned off areas of western Baghdad late on Sunday and searched "suspected terrorist locations", a US military statement said.

Operation Squeeze Play was launched to "minimise insurgent activity in western Baghdad", including Abu Ghraib, the military said, focusing on an area in which fighters have launched numerous attacks, particularly along the 16km airport road and against the US-run detention facility located there.

Airport road is a dangerous strip of highway leading from Baghdad International Airport to the capital's downtown district. It is the scene of regular suicide and roadside bomb attacks aimed at US and Iraqi forces, plus foreigners.

Elsewhere, a car bomber blew himself up near a US convoy and police station in Tikrit, 80 miles north of Baghdad, wounding three US soldiers and two Iraqi policemen, military spokesman Major Richard Goldenberg said.

Also on Sunday, a US soldier was killed in a vehicle accident in northern Iraq, the military said.

Amid the escalating violence, Iraq's government has demanded that Syria do more to stop foreign fighters from crossing the porous border.

Terminally ill

Meanwhile, a senior Iraqi Trade Ministry official has been killed in the ongoing campaign of violence that has killed more than 550 people in less than a month.

Iraqi authorities also announced that Ghazi Hammud al-Obeidi, 65, one of the most-wanted officials from Saddam Hussein's former regime, was released last month because he was apparently terminally ill.

Al-Obeidi, suffering from stomach cancer, was the former regional chairman of the ruling Baath Party in the southern Iraqi city of Kut.

He was detained on 7 May 2003, and released 28 April, making him the first of the 55 most-wanted Iraqis to be freed. He was No 51 on the most-wanted list.

Baghdad crackdown 

The US military has not revealed how many soldiers are taking part in Operation Squeeze Play, which has included house raids and the blocking of roads throughout western Baghdad.

But the number is expected to be at least 2500, predominantly Iraqi.

Also on Sunday, three Romanian journalists and their Iraqi-American guide, who had been held hostage for nearly two months in Iraq, were released.

Separately, Iraqi security forces captured Ismail Budair Ibrahim al-Obeidi, a fighter close to the network of Jordan-born suspected al-Qaida operative Abu Musab al-Zarqawi on Tuesday in Baquba, northeast of Baghdad, a government statement said.

The suspect, also known as Abu Omar, planned car-bomb attacks in Baghdad and rigged booby-trapped cars for foreign fighters, the statement said.

Syria has been accused by the US and Iraq as being the main source of Muslim fighters entering Iraq to try to derail its US backed government.

"Syria can do more," Iraqi government spokesman Laith Kuba said. "It has a regime based on security, intelligence and police" he said, arguing that Damascus must know of the presence of the foreign fighters.

Syrian pressure

"It is impossible for about 2000 people coming from the Gulf to pass through Syria and cross from Qaim or other border points without being discovered, despite our repeated calls," Kutba said.

Prime Minister Ibrahim al-Jaafari said during a trip to Turkey last week that he would soon visit Syria to discuss the issue of foreign infiltration.

Syria has been coming under pressure to stop foreign fighters infiltrating into Iraq, where violence has drastically increased since the 28 April announcement of al-Jaafari's Shia-led government. Syria has always denied the charges.

In other developments on Sunday, senior aides of anti-US cleric Muqtada al-Sadr met a key Sunni group in a bid to soothe tensions that have flared and resulted in the death of 10 Shia and Sunni clerics in the past two weeks, source reported.

Shia-Sunni meeting

The two delegations met at the Um al-Qura mosque, the headquarters of the Association of Muslim Scholars (AMS), west of Baghdad.

The head of the AMS Harith al-Dhari, handed over a document on mediation to a committee delegated by al-Sadr, which attempted to bridge the difference's between the AMS and the Badr Brigades.

The AMS has accused the Badr Brigades of assassinating its imams and worshipers. Several Sunni clerics were killed just last week.

Brigades general secretary Hadi al-Amri has denied the charge and accused the Sunni association of wanting to "push Iraq into a sectarian conflict".

Al-Sadr's return

Al-Sadr said in a television interview aired on Sunday that the talks were aimed at settling the feud between the AMS and the Badr Bridges.

He resurfaced this week after keeping a lower profile following fierce battles last year in the southern holy city of Najaf and Baghdad's impoverished Sadr City between his supporters and US forces.

Al-Kubaisi, the Sunni association official, said he handed al-Sadr's delegation a document committing his group to certain steps, but he did not elaborate. More meetings with al-Sadr's group will be held in the future, he said.

Sunni leaders announced on Saturday they had formed an alliance of tribal, political and religious groups to help Iraq's once dominant minority break out of its deepening isolation following a Shia rise to power after Saddam's ouster.

Sunni obligations

Kuba, the Iraqi government spokesman, said Sunni Muslim leaders should take a strong stand on the killing of security forces and others at the hands of fighters. Sunni groups are believed to be driving Iraq's resistence.

"They should also give their opinion about the killing of civilians," he said. "The Iraqi people want to hear that."

On Sunday, Iraq's Trade Ministry official Ali Moussa and his driver were killed in a drive-by shooting while heading to work, ministry spokesman Faraj al-Jaafari said.

Moussa ran the ministry's auditing office and was a junior official during Saddam's rule.

Sudanese stranded

In a separate development, along the Iraq-Jordan border 72 Sudanese nationals said they were facing harsh conditions after being denied entry into Jordan from Iraq.

Speaking to source, one of the Sudanese nationals said the group comprised 72 people, including women and children. He said they were forced to leave Iraq after receiving death threats to leave the country.

He told source that they faced a severe sandstorm without any protection on Saturday, which caused health problems for many of them, especially the children.

Most of the Sudanese belong to the Darfur region in western Sudan, and they have refused to return, saying it was not safe for them to do so.

The group has appealed to international organisations to transport them to refugees camps in Chad.