KIEV (Reuters) - Ukraine's acting president accused Russia of open aggression on Friday and said it was provoking his country in the same way as it had Georgia before going to war in 2008.
Urging President Vladimir Putin to stop "provocations" in Ukraine's Russian-speaking Crimea, Oleksander Turchinov recalled
Russia's intervention in Georgia over breakaway Abkhazia and South Ossetia, which have large ethnic Russian populations.
Russia's Black Sea fleet has a base in the Crimean port city of Sevastopol.
"Russia has sent forces into Crimea ... they are working on scenarios which are fully analogous with Abkhazia, when having initiated a military conflict, they started to annex the territory," Turchinov said in televised comments.
The war with Georgia lasted five days and Russia remains in control of Abkhazia and South Ossetia, although the United Nations and most countries regard them as still part of Georgia.
"The Ukrainian army will fulfil its obligations but it will not give in to provocations," Turchinov said, adding that he thought the situation would soon be resolved.
"I am personally appealing to President Putin, demanding an end to the provocation and the withdrawal of troops from the Republic of Crimea."
Tensions have increased in Crimea since the ouster of Russian-backed President Viktor Yanukovich, following three months of protests in the national capital Kiev.
Armed men seized two airports in Crimea earlier on Friday and the country's main telecommunications company said landlines and some Internet services were down after fibre optic cables were tampered with.
Some witnesses reported seeing Russian armoured personnel carriers and helicopters, and at least one Russian warship on patrol, although Moscow denied deploying its forces in Crimea.
A representative of Turchinov in Crimea said 13 Russian aircraft had landed on the Black Sea peninsula, and each one had up to 150 personnel on board.
A Reuters correspondent saw at least 20 men wearing the uniform of Russia's Black Sea fleet and carrying automatic rifles surround a Ukrainian border guard post near Sevastopol.
The identity of armed groups that occupied the regional parliament in Crimea and the two airports was not immediately known. Ukrainian officials accused them of being commanded by the Kremlin but Moscow dismissed this.
(Reporting By Sabina Zawadzki and Pavel Polityuk, Editing by Timothy Heritage)