Russia said on Monday that more than 400 Ukrainian soldiers had crossed over onto its territory to avoid fighting with pro-Kremlin insurgents in the east.
A security official said 438 troops had asked Russian authorities to open a "humanitarian corridor" overnight because they were no longer able to defend their positions.
The Ukrainian military confirmed that an undisclosed number of troops had crossed into Russia but denied Moscow media reports they were seeking permanent refugee status.
A spokesman for Russia's powerful Federal Security Service (FSB) said 180 of the troops had since been returned to Ukraine after consultations with Kiev while the rest were deciding what to do next.
"The Russian border guards opened a humanitarian corridor and admitted 438 soldiers of the Ukrainian army" who surrendered their weapons, FSB official Vasily Malayev said, according to Russian news agencies.
A spokesman for Ukraine's campaign against separatist militias said a number of soldiers "were forced to pull back towards a Russian border post following an attempt to break through" rebel lines.
But spokesman Oleksiy Dmitrashkivsky stressed that the troops "did not surrender". He did not specify the number of soldiers involved.
The press office of the Ukrainian border service said according to its information the soldiers had run out of ammunition.
Images broadcast on Russian television station NTV showed dozens of Ukrainian soldiers milling about a tent camp set up at the Gukovo border post.
On Sunday, Russian television broadcast an interview with an unnamed Ukrainian commander who said he led his unit of a dozen troops across the border to save their lives.
Ukrainian forces have stepped up operations in the area near the Russia border in an attempt to encircle the pro-Russian rebels around the cities of Donetsk and Lugansk.
Kiev has accused Russia of supplying weapons to the rebels, a charge Moscow has denied.
Date created : 2014-08-04