Ukrainian Prime Minister Arseniy Yatsenyuk has urged the West not to lift sanctions on Russia for its role in the Ukraine conflict unless the Minsk peace deal is fully implemented.
His call on Saturday came ahead of a meeting of the foreign ministers of Germany, Russia, Ukraine and France in Berlin to prepare for a summit to be held in Paris in early October.
"If you send mixed signals to Putin, for example that we contemplate an idea to lift sanctions ... this is the weakness," Yatsenyuk said at the international Yalta European Strategy conference in Kiev.
"This is the way ... actually to underpin and support Putin in his aggression against Ukraine," Yatsenyuk said in a speech in English.
"Sanctions could be lifted only in one case, if Minsk is fully implemented, if Donetsk, Lugansk and Crimea (are) back (in Ukraine)."
By annexing Crimea in March 2014 and supporting pro-Russian rebels in eastern Ukraine, "Russia undermined and violated an international law", Yatsenyuk said.
"It's entirely unacceptable when a P5 (permanent United Nations Security Council) member constantly violates the UN charter," Yatsenyuk said of Russia.
Kiev and the West accuse Russia of sending regular troops and weapons to aid the separatists in the east, where nearly 8000 people have died in the conflict since April 2014. Moscow has always denied involvement.
In the conflict zone, a total ceasefire was announced starting September 1, and so far appears to be holding.