Ukraine on Wednesday urged its citizens to leave Russia immediately, citing the threat of a Russian invasion that could complicate the provision of consular services.

"Because of the escalating Russian aggression against Ukraine, which can lead to a substantial reduction in possible consular assistance in Russia, the foreign ministry urges the citizens of Ukraine to refrain from travel to Russia, and for those in that country to leave its territory immediately," the ministry said.

Meanwhile, National Security and Defense Council of Ukraine (NSDC) called on Ukrainian parliament or Verhovna Rada to declare state of emergency in all Ukrainian territory apart from separatist-held Luhansk and Donetsk, Secretary of NSDC Oleksiy Danilov said Wednesday.

"The decision was made in accordance with our legislation," he said. "The Verkhovna Rada must approve this within 48 hours. Today I will have a report in the Council on this issue," he added.

According to Danilov, the severity of the emergency regime will vary from region to region.

"Depending on the issues and threats that may arise in certain areas, a stronger or weaker emergency will be introduced," he said.

A state of emergency is imposed by a separate presidential decree, after which it must be approved by the Verkhovna Rada. If necessary, the state of emergency may be extended by the president, but not for more than 30 days.