Russia's Defense Minister says about 500 suspected militants have fled captivity from northeastern Syria since the start of Turkey's offensive in the area.
Defense Minister Sergei Shoigu said efforts are now being taken to apprehend the captives who fled.
"There was a period of more than two days when the camps were not guarded," he said.
"As a result, by our estimates, up to 500 people living in these camps, I don't say that they were all terrorists, they have fled, to put it simply.
"We're told that measures have been taken by those who control this territory to take them back to their home."
Syrian Kurdish forces held thousands of Islamic State group fighters in detention centers in the area and there have been concerns the detainees could escape as Kurds concentrate on defending territory.
Russian President Vladimir Putin, right, and Turkish President Recep Tayyip Erdogan thrash out a deal on the Syrian conflict. Source: Pool Presidential Press Service
Mr Shoigu spoke to reporters on Tuesday in Sochi, Russia, after the Russian and Turkish Presidents made a deal to take shared control of the 440-kilometer Turkey-Syria border.
"Those actions that will be taken and those engagements that have been made within this memorandum will ensure ending the bloodshed, ending the operation that drew contradictory reaction in the world and what's more important it will give to Syrian troops access to the border," he said.
The agreement allows Turkish troops to control the area in northeastern Syria they have taken since Turkey launched its offensive, while Russian military police and Syrian border guards will control the rest of the border.
After marathon talks in Russia's southern city of Sochi, Turkish President Recep Tayyip Erdogan and his Russian counterpart Vladimir Putin announced the deal just hours ahead of a deadline for Turkey to restart its assault on Syrian Kurdish forces.
Syrian government forces deploy near the town of Tal Tamr in northern Syria. Source: AP
The agreement cements Russia and Turkey's roles as the main foreign players in Syria, after US President Donald Trump announced the withdrawal of American forces from the country's north earlier this month.
Mr Putin said the decisions were "very important, if not crucial, to allowing us to resolve the acute situation on the Syrian-Turkish border."
In a phone call to the Russian leader, Syrian President Bashar al-Assad said in reference to the Kurds that "those with separatist designs were responsible for what events have come to".
Mr Shoigu said the Russian military will need to bring in additional equipment to patrol the border to ensure Kurdish fighters withdraw from the 30-kilometer wide area along the frontier.
