The EU leaders, who will first meet Ukraine's new Prime Minister Arseniy Yatsenyuk, are expected to condemn Russia's violation of Ukraine's territorial integrity in the strongest terms, call for Russia to immediately withdraw its troops to its bases in Crimea, and threaten the country with sanctions.

The sanctions mulled by the EU include suspending visa liberalisation and economic cooperation talks with Russia as well as targeted measures in the form of the freezing of bank accounts of Russian officials and a ban on their entry to the EU.

The summit is also expected to confirm a package of financial and economic aid to Ukraine that was proposed by the European Commission on Wednesday: at least EUR 11bn over the coming years to come from the EU's budget and its financial institutions such as the European Investment Bank.

Slovenian Foreign Minister Karl Erjavec told Monday's crisis meeting of EU foreign ministers in Brussels that Slovenia advocated political dialogue and was opposed to sanctions as it believed they could jeopardise diplomatic efforts and could impact negatively on the Slovenian economy.

Bratušek too is expected to call for the need to pursue political dialogue and try to find a peaceful solution to the crisis.