"[Ukraine] has shown determined action and tangible progress in many areas but we are not there yet," he said in a statement. "It would be highly [unfortunate] to slip from the road just before the finish line."
Lithuania hosts a summit next week where the European Union considers association agreements for Ukraine, Georgia and Moldova.
Ukraine passed more than a dozen measures aimed at harmonizing with EU standards. Its government, however, is under pressure to pass legislation that would let jailed Prime Minister Yulia Tymoshenko, an influential opposition leader, get medical treatment outside the country. She was jailed in 2011 for abuse of power in a natural gas deal with Russia's Gazprom.
"We still have 10 days but time is melting away. We know what we want to achieve at the Vilnius [Lithuania's capital] summit and Ukraine knows what it must do for this to become true," Linkevicius said. "I hope that Ukraine will use this week productively and that the necessary laws will be adopted without further delays."
Lithuania holds the annual rotating presidency of the Council of the European Union.