Russian President Dmitry Medvedev arrived on Saturday in the Ukraine's Autonomous Republic of Crimea for informal Commonwealth of Independent States (CIS) summit, RIA Novosti reported.
The informal summit is to take place in the Livadia Palace near the city of Yalta, often used by the Ukrainian leadership to hold solemn international events.
The Belarusian, Armenian and Kazakh leaders have already arrived in the Crimea. Azerbaijani President Ilham Aliyev and his Ukrainian counterpart, Viktor Yanukovych are expected to attend.
The CIS leaders will discuss among the others the development of the Crimea's economy and the investment policy to the autonomous republic.
The summit will be held following Yanukovych's birthday celebrations.
Ukrainian president turned 60 on Friday, but could not invite high-ranking guests yesterday to informally mark the occasion as European Union President Herman Van Rompuy arrived in Kiev on an official visit.
The celebrations are due to be held at a country house in the Crimea.
The CIS, a loose association of post-Soviet countries, consists of Azerbaijan, Armenia, Belarus, Kazakhstan, Kyrgyzstan, Moldova, Russia, Tajikistan, Turkmenistan, Uzbekistan and Ukraine. Georgia pulled out of the organization in 2009.