US Vice President Joe Biden and Ukrainian President Petro Poroshenko spoke by phone on Saturday and both called on Russia and pro-Russian separatists fighting in eastern Ukraine to implement the Minsk cease-fire agreements, the White House said.

Both leaders also welcomed the disbursement of the first tranche of a new International Monetary Fund program for Ukraine, the White House said in a statement.

Germany and other countries want European Union leaders to endorse a declaration saying that EU sanctions on Russia will not be eased unless Moscow complies with a Ukraine cease-fire deal, two officials said.

EU leaders, who meet in Brussels next Thursday and Friday, will discuss the sanctions imposed on Russia's financial, energy and defense sectors in July over Russia's annexation of Crimea and support for separatists in Ukraine.

The cease-fire deal, which was signed last September in Minsk, called for an end to hostilities between Ukrainian forces and Russian-backed separatists and the withdrawal of heavy weapons from the front line.

"It is the plan to have a political declaration to link sanctions to fulfillment of Minsk," said one of the two officials, who asked not to be named.

Germany and some other EU countries were in favor of such a declaration, the officials said, without giving further details.

If EU leaders decide to back this stance, it would effectively extend the sanctions, which expire in July, to the end of the year, as the cease-fire deal requires the restoration of Ukrainian border controls with Russia by year-end.

EU leaders have to be unanimous in their decision to extend sanctions, but a senior EU official said on Friday that they were unlikely to reach a decision at next week's summit.

Some EU governments have only reluctantly backed tough EU sanctions and most want to leave them as they are while they assess the impact of the cease-fire agreement.