KIEV, Ukraine — Pro-Russian separatists in eastern Ukraine agreed Monday to a four-day cease-fire and to further negotiations with the government, a move that could help quell a conflict that has paralyzed the nation and defer further E.U. and U.S. sanctions against Russia.

After the first official meeting between delegates from both sides, Alexander Borodai, the leader of the self-proclaimed Donetsk People’s Republic, said separatist fighters would honor the truce declared last week by Ukrainian President Petro Poroshenko and suspend hostilities until Friday. He also pledged to continue the talks.

Meanwhile, E.U. foreign ministers met in Luxembourg to discuss imposing further sanctions on Russia as early as Friday if the Ukraine situation does not de-escalate and as a similar U.S. sanctions deadline of early July approaches. President Obama and Russian President Vladimir Putin spoke Monday about the conflict, the White House said.

The Ukrainian National Security and Defense Council said Monday that things had quieted during the day after shelling from pro-Russian forces over the weekend. But in a conflict in which separatists have often fought among themselves, it was not clear whether the cease-fire would be observed by all those who have taken up arms against the government and seized control of administrative buildings and territory in the east.

The Monday meeting in the regional capital of Donetsk was attended by Donetsk separatist leaders, the head of the Ukraine mission of the Organization for Security and Cooperation in Europe, Russia’s ambassador to Ukraine and former Ukrainian president Leonid Kuchma, among others. Poroshenko sent Kuchma, a conciliatory figure from eastern Ukraine who was president from 1994 to 2005, as his representative.

Last week, Poroshenko announced the cease-fire and offered a peace plan that he said would give more power to Ukraine’s regions, a key demand of the industrial heartland in the east.