Western leaders have condemned a referendum on independence celebrated in eastern Ukraine on Sunday, as pro-Russian rebels declared a resounding victory claiming more than 90% of votes in favour.
However, there seemed to be some confusion amongst voters as to whether the vote meant independence from Ukraine or eventual union with Russia.
After declaring the vote illegal on Sunday, EU foreign affairs ministers meeting in Brussels on Monday might announce additional measures.
Earlier this month, the EU threatened Moscow with more sanctions if Russia disrupts a presidential election in Ukraine planned for May 25.
Meanwhile, European Council President Herman Van Rompuy is in Kiev holding talks with the Ukrainian Government.