(QHA) -

German Chancellor Angela Merkel and French President Francois Hollande are due to discuss the situation in eastern Ukraine amid renewed fighting which puts in danger a cease-fire deal brokered by the two leaders last week, AP reports.

Merkel and Hollande, who have been the key international negotiators in the crisis, are meeting on February 20 in Paris, ahead of an upcoming summit of the Group of 20. 

On February 19, shelling was reported in the rebel-held city of Donetsk, with artillery fire shaking buildings in the city center.

Ukrainian military spokesman Anatoliy Stelmakh said rebels heavily shelled government-held positions in Shyrokine, near the strategic coastal town of Mariupol, which is under government control.

The latest fighting came after government troops withdrew from the strategic town of Debaltseve following weeks of intense fighting against Russian-backed separatists.

The rebel advance, which defied the cease-fire signed in Minsk on February 12 following marathon negotiations brokered by Germany and France, has been widely condemned.

But Russia and the separatists insist the rebels' actions in Debaltseve did not violate the cease-fire because the town was encircled by rebel forces at the time of the agreement, something Kyiv rejects.

The United States said on February 19 that it was "deeply troubled" by reports of continued fighting.