A building damaged by shelling is seen in the eastern Ukrainian city of Slaviansk on June 25, 2014. Reuters/Shamil Zhumatov

(Reuters) - US Secretary of State John Kerry, after meeting with France's foreign minister, said on Thursday Russia should call on separatists in Ukraine to disarm within "the next hours."

"We are in full agreement that it is critical for Russia to show in the next hours, literally, that they're moving to help disarm the separatists, to encourage them to disarm, to call on them to lay down their weapons and to begin to become part of a legitimate process," Kerry told reporters in Paris.

He added that EU leaders would discuss possible sanctions moves on Russia at their summit in Belgium starting Thursday.

"We all agree that they need to be ready. But our preference is not to have to be (in) a sanctions mode. We would like to see a cooperative effort between the United States, Europe and Russia and the Ukrainians," he said.