Foreign ministers from Ukraine, Russia, France and Germany are due to meet in Berlin today amid escalating tensions in eastern Ukraine.
German Foreign Minister Frank-Walter Steinmeier says the meeting aims to renew a political compromise under increasingly difficult circumstances.
The forthcoming Berlin meeting comes as Kiev accuses Russia of attacking Ukraine forces in the eastern Luhansk region, which borders Russia.
Ukrainian President Petro Poroshenko says de-escalation of the conflict in Ukraine will never happen while Russian forces continue to enter his country.
"As far as today our intelligence report two battalions of Russian tactical groups, total number up to 2,000 troops, entered my territory, and not simply entered but participated in the combat operation. I think with this type of approach we'll never reach the de-escalation."
There has been no independent confirmation of the latest Ukrainian allegations, which have been denied by Russia.
The European Union has announced that it will not consider easing sanctions against Russia as long as the fighting continues.
