Moscow was outraged at an attack in Iraq on a convoy carrying injured Syrian military personnel that killed more than 50 people, the Russian Foreign Ministry said Tuesday.

"This criminal act in Iraqi territory was perceived with outrage in Moscow," ministry spokesman Alexander Lukashevich said in an online comment.

A total of 48 Syrian servicemen and nine Iraqi law enforcement officers were killed in the ambush, which occurred in Iraq's Anbar province near the border junction of Syria, Iraq and Turkey, according to Iraqi authorities.

Earlier reports said the wounded Syrian government soldiers were being escorted back to Syria after having hidden on the Iraqi side of the border.

"It is too bad that Syria's internal conflict has started spreading outside the country, creating a direct threat to the neighboring states' security," Lukashevich said.

"It is highly dangerous that terrorists act more and more freely in the trans-border space," he said.

Russia has called for more efforts to launch a dialogue between Syria's government and opposition and to make a decisive response to terrorism.