MINSK, Belarus (AP) — A European official confirms that Ukraine and the Russian-backed rebels have signed a cease-fire deal that takes effect in less than two hours.

The announcement -- which confirmed a Twitter posting by the rebels -- came as representatives of Ukraine, Russia, the rebels and the Organization for Security and Cooperation in Europe met in Belarus.

The official from the OSCE said the cease-fire would take effect at 11 a.m., Eastern time.

Since mid-April, Moscow-backed separatists have been fighting government troops in eastern Ukraine in a conflict the U.N. estimates has killed nearly 2,600 people.

Yesterday, a NATO military officer told The Associated Press that the ranks of Russian soldiers directly involved in the conflict have grown.

Associated Press reporters today heard heavy shelling north and east of Mariupol (mah-ROO'-pahl), a key Ukrainian port on the Sea of Azov, between Russia and the Crimean Peninsula -- which Russia annexed in March. The shelling appeared to indicate that rebels had partially encircled the area and were probing its defenses.