Combined Russian-separatist military forces are shelling Shyrokyne near Ukraine's strategic port city of Mariupol in southeastern Ukraine in an attempt to force Ukrainian government troops to retreat from the strategic town.

"Despite the ceasefire, Russian hybrid forces continue firing at Ukrainian government troops in the Anti-terrorism Operation (ATO) zone, the ATO press center said.

Shelling is almost non-stop from militant groups, according to a Ukrainian marine commander, who said fighting continues.

"There hasn't been any ceasefire. In addition to rifle fire, the militants are firing heavy weapons, including anti-tank missiles, everything at their disposal, even artillery rounds," the commander said.

ATO HQ said the situation in Shyrokyne remains tense: "The Russian hybrid forces are trying to force our units from Shyrokyne, however the marines are successfully holding their positions."