Officials in the Ukrainian port city of Mariupol say an array of artillery attacks hit areas near the city during the morning, as the deadline for a cease-fire creeps closer.

The city's press service reported a half-dozen rocket and mortar attacks on outlying areas Saturday morning. There was no immediate information on casualties.

Mariupol is on the Azov Sea and concerns are strong that Russian-backed separatists aim to seize it as a step toward establishing a corridor between mainland Russia and the Crimean Peninsula that Russia annexed 11 months ago.

Under an agreement reached this week, rebels and Ukrainian forces are to observe a cease-fire beginning at midnight (2200 GMT, 5 p.m. EST).