BRUSSELS, Dec. 13 (Xinhua) -- The European Council on Thursday voiced its support for Ukraine regarding tensions between Russia and Ukraine in the Kerch Strait and the Azov Sea but announced no further measures against Russia.

Heads of the European Union (EU) states and governments met on Thursday, the first day of their two-day summit, in Brussels. Conclusions from the first day addressed the ongoing standoff between Russia and Ukraine, and attributed the acts of Russia to "violations of international law."

"There is no justification for the use of military force by Russia," said the European Council, demanding the immediate release of all detained Ukrainian sailors, the return of the seized vessels and free passage of all ships through the Kerch Strait which controls access to the Azov Sea near Crimea.

"The EU stands ready to adopt measures to strengthen further its support, in particular in favor of the affected areas of Ukraine," said the European Council.

On Wednesday, the European Parliament adopted a non-biding resolution calling on the EU and its member states to introduce targeted sanctions against Russia "if the Ukrainian servicemen are not released and if there is any further military escalation."

Tensions between Russia and Ukraine have been escalating since last month when Russia seized three Ukrainian ships near the Kerch Strait, saying the Ukrainian ships breached its border.

The Ukraine side called Russia's actions an "act of aggression" and imposed a martial law in certain regions of the country for 30 days starting Nov. 28.