Russian Foreign Minister Sergei Lavrov said Thursday the top priority in the Ukraine crisis was an immediate ceasefire, not the format of talks with Russia.

The first and foremost task was to stop the violence and begin dialogue with all regions in Ukraine involved, Lavrov said.

Russia and Ukraine were maintaining political contacts "at different levels and in different formats" to push for an immediate end to violence and "start a true rather than a pretend dialogue," the minister said.

Meanwhile, Secretary General of the Organization for Security and Cooperation in Europe (OSCE) Lamberto Zannier, who was in Russia, called for all sides to stop street fights and sit down for negotiations.

The OSCE was involved in the negotiating process with all sides in the ongoing conflict, Zannier said while visiting a refugee camp in the Rostov region of southwestern Russia on Thursday.

The ongoing conflict between the Ukrainian government and insurgents has raised international concern. Ukrainian President Petro Poroshenko said Sunday negotiations had started in Kiev among Ukraine, Russia and the OSCE.