Ukrainian Prime Minister Arseniy Yatsenyuk warned EU leaders on Thursday to keep the pressure on Russia and not allow President Vladimir Putin to exploit their differences over sanctions.
"If Putin splits the unity among EU member states and among the leaders of the EU, this will be the biggest success story for Putin and a disaster for the free world," Yatsenyuk said ahead of a summit of European leaders in Brussels.
Putin's aim "is the instability of the EU," he added after a meeting with European Union president Donald Tusk, a former Polish premier who has taken a hard line on sanctions.
EU leaders meet later Thursday to review sanctions against Russia as a tenuous ceasefire accord brokered by France and Germany in February continues to hold in east Ukraine.
The immediate issue is whether to extend the tough economic sector measures adopted after the July shooting down of a Malaysia Airlines plane over eastern Ukraine which the West blamed on pro-Moscow rebels.
Some of the 28 EU member states want the summit to agree to extend these economic sanctions to end-2015, linking them to the timeline -- and the success or failure -- of the February Minsk ceasefire accords.
Others believe the bloc should wait to see how the situation develops on the ground, leaving a rollover decision to the June EU summit, or even until July.
Diplomatic sources said the most likely outcome is that EU leaders ask the European Commission, the EU's executive arm, to begin work so the sanctions can be rolled over in June.
"New sanctions will not happen," one of the sources added. Sanctions have been contentious from the start of the Ukraine crisis, with some EU member states such as Germany and Italy reluctant to go too far for fear of damaging important trade and political ties with Russia.
In contrast, Britain and many of the former east European states once ruled from Moscow have backed a tougher line.
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