A woman has died and at least four people have been injured when fighting flared again in eastern Ukraine.
The fighting commenced overnight jeopardising a ceasefire struck less than two days earlier between Ukrainian government forces and pro-Russian separatists.
The accord, brokered by envoys from Ukraine, the separatist leadership, Russia and Europe's OSCE security watchdog, is part of a peace plan.
The peace plan was intended to end a five-month conflict that has killed nearly 3,000 people.
It has caused the sharpest confrontation between Russia and the West since the Cold War.
Shelling resumed near the port of Mariupol on the Sea of Azov late on Saturday night.
It was just hours after Russian President Vladimir Putin and Ukrainian counterpart Petro Poroshenko had agreed in a phone call that the truce was holding.
Fighting also broke out early this morning on the northern outskirts of rebel-held Donetsk, the region's industrial hub.
The two cities turned quiet again this afternoon.
Both sides insisted they were strictly observing the ceasefire and blamed their opponents for any violations.
Earlier, government forces said they had come under artillery fire east of Mariupol, a crucial port for Ukrainian steel exports.
In the days before the ceasefire they had been trying to repel a big rebel offensive against the city.
The shelling in Mariupol claimed the first civilian casualty since the ceasefire began. Local officials confirmed the death of a 33-year-old woman early today and said at least four other people had been wounded.
Meanwhile, in Dublin a pro-Ukrainian rally was held by a group who wish to highlight the sale of the "Vladivostok" mistral.
They are concerned over the move of the President of France Francois Hollande selling the Mistral ship to Russia.