KIEV - Shelling by Russian-backed separatists killed at least two people -- one civilian and one Ukrainian serviceman -- in Ukraine at the weekend and halted production at one of Europe's largest coke plants, the police and military said.

Police said the civilian was killed and two women wounded when Avdiyivka, a government-held town near the frontline, came under intense shelling by separatists. A member of the National Guard was killed and two other guardsmen were wounded on Sunday at Shyrokyne, near the strategic port city of Mariupol, a military spokesman told 112 TV channel.

The weekend attacks put fresh strain on a tenuous ceasefire which has been regularly violated since it was brokered by the leaders of Ukraine, Russia, Germany and France last February.

The attacks at Avdiyivka closed down a major coke-producing factory owned by Ukrainian steelmaker Metinvest. Producing 40 percent of Ukraine's coke, it is the main employer in the town and has become a target for the separatists since they took up arms against the government last April.

Last week, a worker there was killed and two wounded in what Metinvest described as the heaviest shelling since the declaration of the ceasefire. "This is the second powerful bombardment in the past few days ... The business has been stopped as a matter of urgency. Coke production is halted," Metinvest said in a statement on its website. "As soon as the situation stabilises, work to restore power supply to the factory will begin."

Damage to internal rail tracks at Avdiyivka meant the factory was not able to bring in raw materials or ship out finished products, Metinvest, which is Ukraine's largest steel firm, had said on Friday. "The town is without electricity and running water," the head of Donetsk regional police Vyacheslav Abroskin said in a Facebook post on Sunday. "One young man was killed and two women seriously wounded," he said.

Any production outages at the coke plant will threaten output at Ukraine's steel plants, including two of the largest in Mariupol. Military spokesman Dmytro Gorbunov told 112 TV channel that rebels used large-calibre artillery and rockets in Sunday's attack at Shyrokyne, near Mariupol. Shyrokyne, a small town on the Sea of Azov coast, is disputed by separatist and government forces and has become a regular flashpoint where a three-month ceasefire is regularly flouted.