MOSCOW — More than 400 Ukrainian soldiers crossed into Russia, officials from Russia and Ukraine said Monday, although the two sides gave conflicting accounts as to why they did it.
The Russian official said the soldiers deserted the Kiev government and the Russian side opened a safe corridor. A Ukrainian military official said the soldiers were forced into Russian territory by rebel fire after running out of ammunition.
Pro-Russia separatists in eastern Ukraine have been battling the Kiev government since April, a conflict that has claimed at least 1,129 civilian casualties, according to a UN estimate.
Vasily Malayev, head of Russia’s Federal Security Service’s border patrol in the Rostov region, said that 438 Ukrainian soldiers had crossed into Russian territory on Monday. He said the Russian side had allowed the soldiers to safely enter the country overnight.
Malayev later said that 180 of them requested to return to Ukraine and were being sent there in buses. He said the move was not an exchange but did not give further details.
Russia’s Defense Ministry couldn’t immediately be reached for comment.
The Ukrainian military confirmed that part of a brigade had most likely crossed into Russian territory, although it disputed Russia’s version of events and could not confirm the exact number.
A spokesman for the operation in the east, Oleksiy Dmitrashkovsky, said troops from the army’s 72d Brigade entered Russian territory because they were penned into their position and came under a sustained barrage of fire from separatist forces.
Rebel fighters used tanks, mortars, artillery, and Grad missile launchers over four hours, Dmitrashkovsky said, and eventually the brigade was forced to divide into two sections.
‘‘One was meant to break out and join forces with a support unit. The other unit had the task of providing fire cover,’’ Dmitrashkovsky said. ‘‘In doing that they fired their weapons until no ammunition remained, after which they abandoned their position and reached a place near a border crossing on Russian territory.’’
Also Monday, the Interfax news agency reported that Russia’s air force began military drills in central and western regions of the country, a move that could spark further fears about Moscow’s intentions.
The drills will last through Friday, air force chief Igor Klimov was reported as saying, and will involve more than 100 fighter jets and helicopters.
Ukraine and Western countries have accused Russia of providing the rebels with equipment and expertise, a claim the Russian government has repeatedly denied.
The West has also accused Russia of most likely providing the insurgents with surface-to-air missiles that may have been used to shoot down a Malaysia Airlines passenger jet over rebel-held territory on July 17, killing all 298 people on board.
A Dutch plane carrying victims’ remains from the disaster took off from Kharkiv on Monday. The plane was also carrying personal belongings of victims to the Netherlands.
Fighting continued Monday between government forces and rebels defending the separatist strongholds of Donetsk and Luhansk.
The Ukrainian army was tightening its ring around Donetsk and moving closer to a major assault to recapture the city, warning civilians to leave.
In Luhansk, officials said the power grid was completely down Monday and the city is running out of fuel. Luhansk residents said store shelves are emptying fast, and those who haven’t managed to flee must drink untreated tap water.
With little medicine left, doctors were sending patients home.