Moscow says the killing of a Russian TV cameraman in eastern Ukraine just before a cease-fire is due to expire shows Kyiv does not want to de-escalate the conflict.
The Russian Foreign Ministry said the shooting of cameraman Anatoly Klyan on June 30 shows Kyiv is undermining the current cease-fire before it ends at 10 p.m. Kyiv time.
Klyan, 68, was shot while filming near a pro-Kyiv military unit in the Donetsk region.
The origin of the gunfire that killed Klyan is unclear.
He is the third Russian journalist to die in the conflict and the fifth journalist overall.
French President Francois Hollande and German Chancellor Angela Merkel are expected to phone the presidents of Ukraine and Russia on June 30 to support extending the cease-fire.
They also phoned Ukraine's Petro Poroshenko and Russia's Vladimir Putin on June 29 in a conference call that lasted more than two hours.
The French president said in a statement that the leaders on June 29 discussed "the importance of making new concrete advances in the security situation on the ground, prolonging the cease-fire, and putting in place the peace plan" presented by Ukraine.
The Kremlin said the four leaders called on Poroshenko to extend the truce in the country's east beyond June 30.
A statement from Poroshenko's office said he had called on Putin to strengthen Russian control over its borders to prevent militants and arms from entering Ukraine.
The conversation on June 29 came after reports of renewed clashes in eastern Ukraine, where security forces have been battling pro-Russian separatists.
Ukraine's military said five soldiers were killed and at least 17 injured in the Donetsk and Luhansk regions at the weekend.
Rebels also seized an air-defense unit in Donetsk and took several servicemen prisoner.
Meanwhile, several thousand demonstrators gathered on June 29 outside the presidential administration building in Kyiv to demand an end to the cease-fire.
The demonstrators said the cease-fire is only giving the rebels time to regroup and rearm.
They also demanded that Poroshenko declare martial law in eastern Ukraine, give sufficient weapons to volunteer battalions to fight the "terrorists," and social guarantees for servicemen involved in the army's military operation in the east.
Merkel has warned Moscow that the EU is prepared for "drastic measures" if no progress is made on Poroshenko’s 15-point peace plan, which involves decentralizing power and holding early local and parliamentary elections.
With reporting by dpa, Interfax, and Reuters