It's time to develop and launch an international negotiation mechanism for the de-occupation of the illegally annexed Ukrainian Crimea, said Ukraine's representative to the EU Nikolai Tochitsky.

"Russia must abolish all its illegal decisions that led to the occupation of the Crimea," wrote Tochitsky for EUObserver.

He added that the EU should be ready to step up diplomatic and political pressure on the Russian Federation, in particular by strengthening sanctions, to show that the EU will not stand aside and will not allow violations of human rights.

Earlier, Lithuanian President Dalia Grybauskaite on the third anniversary of the illegal annexation of Russia by the Ukrainian Crimea once again supported the territorial integrity of Ukraine.