Baghdad (CNN) -- Some 48 Syrians, most of them soldiers, and nine Iraqi soldiers were killed Monday in an attack near the western Iraqi town of Ar Rutbah, an official said, raising concerns that Syria's civil war could spill over into Iraq.
The Syrian soldiers' convoy was ambushed by gunmen using roadside bombs and machine guns.
"From the beginning, we have warned that some militant groups want to move the conflict in Syria to Iraq," said Ali al-Mussawi, adviser to Iraqi Prime Minister Nuri al-Maliki.
"Militant groups are very active on the border areas between Iraq and Syria. Some of these groups affiliate with al Qaeda in Iraq," he added.
Al-Mussawi said that many of the Syrians killed in the ambush had earlier received medical treatment in Iraq. They were wounded during a battle at the Yaarabiya-Rabia border crossing a few days ago. The point is called Rabia in Iraq; Yaarabiya in Syria.
According to security officials in Ramadi, Iraq, several Syrians were wounded in that battle between the Free Syrian Army and Syrian soldiers.
Dozens of Syrian soldiers and officials took refuge in Iraq by surrendering to that country's army on Friday after rebels took over the Yaarabiya post, the officials said.
They added that the convoy had been headed from Rabia to the al-Waleed border crossing in Iraq's Anbar province when it was attacked.
The United Nations has estimated that about 70,000 people have been killed in Syria's civil war, which began roughly two years ago.
Just on Monday, at least 149 people were killed, according to the Local Coordination Committees of Syria, an opposition group. The deaths include 40 in and around Damascus, 35 in Raqqa province and 25 in Aleppo.