Prime Minister Ibrahim al-Jaafari, appearing on Friday with visiting US Secretary of State Condoleezza Rice, said it was no secret that foreign fighters were using Syrian territory to enter Iraq and the government had implored the Syrians to crack down on such movements.
"We ask why the Syrians are not responding to our people's demands," al-Jaafari said. "We demand that they control their borders, prevent infiltration and terrorism. We want good relations with Syria, but this cannot be achieved when such violations exist."
US troops launched a major offensive last week against al-Qaida-led fighters near the border with Syria, an area the US command describes as the major entry point for foreign fighters responsible for many of the attacks that have killed hundreds of Iraqis in recent weeks.
The American command reported on Friday that a US marine was killed the day before in a roadside bombing in Karabila, about 200 miles (322km) west of Baghdad and one of the main border area villages where the fighters operate.
Two US army soldiers were killed on Thursday by small arms fire during combat in Khaldiya, 88km west of Baghdad, the military said. Two other American soldiers died in a traffic accident northwest of Kirkuk, the military said.
The deaths brought the number of US service members killed in Iraq since the war began in 2003 to 2061, according to an Associated Press count.
Syria maintains it has tried to curb infiltration across its borders and has accused US and Iraqi forces of failing to do their part to control the long desert frontier.
President Bashar al-Assad says
the US is discrediting Syria
The Syrians insist allegations against them are part of a US media campaign to discredit their government for opposing the Iraq war.
Elsewhere, three Iraqi police officers were killed Friday when their vehicle was ambushed near Baquba, 56km northeast of Baghdad.
Arrests in Diyala
The Iraqi army has arrested more than 200 Iraqis in Diyala province, sources in Diyala governorate told Aljazeera.
The military operation comes after US forces arrested 390 of the area's residents a few days ago, the sources added.
Diyala's deputy governor said local officials had not been notified of the army's operation and denounced the arrests, saying they targeted regional Sunni leaders.
"It aims to prevent Sunnis from participating in the coming elections"
Aouf Abd al-Rahman,
Diyala deputy governor
"It aims to prevent Sunnis from participating in the coming elections," Aouf Abd al-Rahman told Aljazeera.
"This campaign has targeted Sunni members of the governorate council, including Muhammad Kamil, Baquba suburb commissioner Khalid al-Sanjari, the head of the Iraqi Islamic Party relations department in Diyala, the head of the Iraqi Islamic Party in the Bani Saad area and the deputy chief judge in Diyala," he said.
None of those arrested are criminals or terrorists, Abd al-Rahman said.
He warned that the arrests would discourage Sunnis from participating in Iraqi elections.
In Baghdad, armed men fired on the compound of the Omani embassy, killing two people and wounding two others - the second fatal shooting involving employees of Arab embassies in Baghdad this week.
One of the dead was a police officer and the other an embassy employee, said police Major Falah al-Muhammadawi said.
The fate of the two Moroccan
embassy staff remains unknown
On Wednesday, a driver for the Sudanese embassy was shot dead in the same part of the capital, and last month two employees of the Moroccan Embassy were abducted on a highway in western Iraq.
Al-Qaida in Iraq, led by Abu Musab al-Zarqawi, said it abducted the Moroccans, and carried out the July kidnap and killing of three Arab diplomats - two Algerians and one Egyptian - in Baghdad.
The organisation has warned governments, especially those of Arab and Muslim countries, to break off ties with the US-backed Iraqi government.
Politician's brother arrested
Meanwhile, Razgar Ali, the head of the Kirkuk provincial council, said a brother of parliament speaker Hajim al-Hassani had been arrested by US and Iraqi forces for leading a terrorist cell.
Hatam Mahdi al-Hassani initially was reported kidnapped along with two others. Another brother, Nashat al-Hassani, denied Hatam was involved with terrorists.
"We are a religious family and we have no relations with insurgents. We demand his immediate release, if he is under police custody," Nashat al-Hassani said.
US forces also reported a raid on Thursday on an fighter cell responsible for bombings in which seven men were killed, including one wearing a vest loaded with explosives.
"Coalition forces, acting on multiple intelligence sources and tips from local citizens, raided three suspected terrorist safe houses," the statement said.
"During the raid, coalition forces killed seven terrorists and detained five. The terrorists were armed with rocket-propelled grenades, machine guns and explosives."