Moscow: Russia has accused Ukraine of abducting two Russian servicemen on the annexed Crimea peninsula, but Kiev said it had merely detained two Ukrainian army deserters.
In a statement carried late Monday by local news agencies, the Russian defence ministry said servicemen Maxim Odintsov and Alexander Baranov were "illegally detained and removed from Crimea by Ukrainian security forces" on Sunday.
"We consider that these actions of the Ukrainian special forces toward Russian citizens are yet another gross provocation and demand their immediate return to Russian territory," the statement said.
The Security Service of Ukraine (SBU) meanwhile said the two men were "former Ukrainian servicemen who betrayed their oath and went to serve in the Russian military after the illegal annexation of Crimea," the Interfax-Ukraine news agency reported.
The SBU added that the men stood accused of "desertion and treason" and had been detained "after crossing the border" between Ukraine and Russian-annexed Crimea.
Russia seized Crimea in 2014 by sending in thousands of special forces to take control of Ukrainian bases and holding a hastily organised referendum that was rejected by the international community.
The move shattered ties between the two ex-Soviet neighbours and sent relations between Moscow and the West plummeting to their lowest point since the Cold War.
In August, President Vladimir Putin accused Ukraine of attempting armed incursions into the disputed region.
Russia`s security agency said at the time it had thwarted "terrorist attacks" in Crimea by Ukrainian military intelligence and beaten back armed assaults, but Kiev furiously denied the incidents.
The allegations ratcheted up tensions in the feud between Russia and Ukraine sparked by Moscow`s seizure of the Black Sea peninsula and sparked fears of a wider conflict.