Russian President Vladimir Putin has called for a "comprehensive" dialogue among all the conflicting parties in the crisis in eastern Ukraine that has killed hundreds.
Putin spoke on Sunday with French President Francois Hollande and German Chancellor Angela Merkel, who urged Putin to back talks between Kyiv and rebels in eastern Ukraine.
Putin later Sunday called for Ukraine's leadership and rebels to start genuine dialogue, saying Kyiv should halt military operations and guarantee the rights of Russian speakers in the separatist east, who must feel like they are "an integral part'' of Ukraine.
The Russian leader said that he welcomed the week-long cease-fire called by Ukrainian President Petro Poroshenko.
But, Putin said, "unfortunately," there appeared to be artillery fire "from the Ukrainian side" late Saturday, a day after Poroshenko said the unilateral cease-fire would begin.
Putin told Merkel and Hollande the Ukraine peace plan should be "reinforced by a real cease-fire," the Kremlin said in a statement on Sunday.
For their part, Merkel and Hollande urged Putin to ensure full control of its border with Ukraine to avoid the infiltration of more military equipment and armed men into eastern Ukraine.
Peace plan
Poroshenko laid out a peace plan late Saturday, urging all parties to support the plan and settle their differences through dialogue.
He said he would negotiate with separatists who are not implicated in "murder and torture" in eastern Ukraine.
Earlier Saturday, pro-Russian separatists rejected Ukraine's unilateral cease-fire.
Ukraine's border guard service said rebels attacked one of its posts in the Donetsk region, hours after Poroshenko ordered the halt in fighting.
At least three troops were wounded.
A group of fighters with the self-proclaimed Donetsk People's Republic gathered in the Donetsk town square Saturday to take a military oath to defend their land.
Kyiv expressed concerns after Putin put troops in central Russia on "combat alert" for snap drills. Russian officials say the drills involve some 65,000 troops.
Poroshenko's cease-fire ordered Ukraine's military and security forces to halt their operations against separatists for seven days. But he said the order did not mean Ukrainian forces would not fight back if attacked.
A NATO military officer told VOA Friday that the new Russian troops near the border with Ukraine do not appear to be engaged in "border patrol" duties, but instead seem to be concentrating in staging areas and preparing and awaiting future orders.
He said this is not "an encouraging sign."
But Kremlin spokesman Dmitry Peskov said the deployment had been planned in advance and was designed to reinforce Russia's border controls.
Ukraine and Russia have been locked in a tense standoff since late February when Russian forces moved into the Crimean Peninsula. Russia annexed Crimea from Ukraine in March, and in April, the pro-Russian insurgency erupted in Ukraine's east.