Two Russian warships passed through the Bosphorus Strait of Turkey en route to a Black Sea on Tuesday after Russia summoned the two warships over crisis between Kiev and Moscow, private Dogan news agency reported.

The 150 'Saratov' landing ship and the 156 'Yamal' assault ship crossed the strait around 07:30 local time (0530 GMT), the agency reported.

No coast guard boats were seen escorting the warships ships, the Anatolia news agency reported on Tuesday. Russia summoned the two warships to its Black Sea fleet after it started to strengthen its military presence in the Crimea.

The Ukrainian crisis, which originated from protests against President Viktor Yanukovych's decision last November to put on hold an association agreement with the European Union to get Russian aid, took an abrupt turn in the past two weeks following bloody clashes between protesters and police. Yanukovych was ousted by the parliament and had to flee to Russia.

The mostly Russian-speaking Crimea is now the epicenter of the ongoing crisis. Some 50 armed men carrying Russian navy flags took control of two airports in the Crimean capital of Simferopol on Friday, one day after gunmen seized the local parliament and government buildings.