欧盟将对俄罗斯实行严厉制裁
European Union leaders are due to meet in Brussels to discuss further targeted sanctions in response to Russia's annexation of Crimea from Ukraine.
俄罗斯合并乌克兰的克里米亚地区，对此欧盟国家领导人将在布鲁塞尔开会讨论对其实行进一步针对性制裁。
It comes as UN chief Ban Ki-moon visits Russian leaders in Moscow to urge a diplomatic solution to the crisis.
Tensions are high in Crimea, where pro-Russia forces seized two bases on Wednesday including Ukraine's navy HQ in Sevastopol.
Ukraine's navy commander was detained, but has now been released.
Crimean leaders signed a treaty with Moscow on Tuesday to absorb the peninsula - an autonomous republic in southern Ukraine - into Russia, following a disputed referendum on Sunday.
Russia's Foreign Minister Sergei Lavrov said the process was expected to be completed this week, Russia's Interfax news agency reports .
He said Russia was protecting the rights of Russians, and would continue to "insist their rights and freedoms are observed fully in the countries where [our] compatriots are living".
The crisis comes nearly a month after Ukraine's pro-Russian President Viktor Yanukovych was replaced by Western-leaning interim authorities.
Thousands of Ukrainian soldiers and sailors remain trapped inside military bases on the peninsula, surrounded by heavily armed pro-Russia forces.