Russian President Vladimir Putin on Friday arrived in annexed Crimea, Russian news agencies reported, days after he accused Kiev of attempting an armed incursion into the peninsula.

Russian President Vladimir Putin on Friday arrived in annexed Crimea, Russian news agencies reported, days after he accused Kiev of attempting an armed incursion into the peninsula.

Putin is to chair a meeting of his powerful security council in Crimea and visit a youth forum on his fifth visit to the strategic Black Sea peninsula since annexing it from Ukraine in March 2014.

The visit comes after Putin last week lashed out at Kiev over an incident on the frontier between Crimea and Ukraine, accusing it of "practicing terror" and sending a group of saboteurs into Crimea ahead of the elections.

Two Russian officers were killed in the incident, in which Ukraine denied any involvement.

Ukraine's President Petro Poroshnko on Thursday said he considered the likelihood of an escalation "high" and could not rule out a "full-scale Russian invasion along all fronts."

Kiev said Thursday heavy rebel shelling killed three soldiers in its east, where the government has been battling pro-Russian separatists since 2014.

Western leaders expressed alarm at the possibility of any escalation.