Reduced to drinking rainwater, their houses rattled by artillery blasts despite a ceasefire, villagers on the frontline of Ukraine's eastern conflict are pleading for the forces to withdraw.

But with deadly exchanges of fire mounting over recent days, government soldiers stationed among the missile craters warn that would allow an advance by the pro-Russian rebels who have taken control of much of the east.

"What we want most of all is for the troops to be withdrawn, for observers to come and for us to live in peace," said Lyudmyla, a retired woman of 64 in Berdyanske, a southeastern seaside village on the coast of the Azov Sea.

It lies a few kilometres east of the key port of Mariupol -- the biggest remaining government-held city in the conflict zone.

Berdyanske's beaches drew tourists from as far as way as Siberia before fighting between Ukrainian government forces and pro-Russian rebels broke out a year ago. Since then the conflict has killed more than 6,000 people.

Now the village shop is closed and Lyudmyla and her husband are among the few residents not to have fled.

"This is our homeland. We have nowhere else to go," said Lyudmyla, who would not give her second name, as she stood in slippers hanging out laundry in her back yard.

- Flare-up in fighting -

Fighting flared up this week less than a kilometre away, in Shyrokyne, a village right on the front line, where the holiday homes that once drew visitors have broken windows and holes blasted in their walls.

"We really need water. We drink rain water... We drink tea and cook with it," said another local woman who would not give her name.

"The only well is near the hospital, but that street has been bombarded and we cannot go there."

The missiles were meant to halt under a ceasefire brokered by Germany and France in February.

"Truce? What truce? You can hear the sound of machine guns. From the other side you can hear heavy arms," said Tatyana Batikova, a farmer in Shyrokyne.

"They fired on us yesterday and the day before. Yesterday an explosive flew into the house," she added. "I'm afraid to even talk about it because I don't know what might happen to me."

The foreign ministers of Ukraine, Russia, Germany and France on Tuesday expressed "grave concern" over surging violations of the ceasefire.

Under the ceasefire, all guns over 100mm calibre were meant to be withdrawn from the frontline, but European OSCE monitors say both sides have breached that requirement.

The ministers renewed their call for the withdrawal of all such weapons and extended the appeal to include "heavy weapons below 100mm" and tanks.

- Calm before the bombardment -

The OSCE has suggested demilitarising Shyrokyne.

A Russian military representative monitoring the ceasefire, Alexander Lentsov, said Wednesday the Russian and Ukrainian sides had agreed to pull back their tanks, artillery and mortars 15 kilometres on each side to make a 30-kilometre (19-mile) buffer zone, Russian news wires reported.

But Ukrainian soldiers said they were loath to give up their positions even though they are in range of pro-Russian forces whom they accuse of bombarding them with mortars of 120 and 152 millimetres.

"The other side doesn't respect any agreement," said one Ukrainian officer in Berdyanske, going by the nom de guerre San Sanych, pointing to craters blown out of a road, he says, by these missiles.

"If we withdraw, they will press on into here."

The Ukrainian soldiers enjoyed a lull on Wednesday at their makeshift command post in a half-built house in Berdyanske, playing board games, their Kalashnikov rifles laid nearby.

One shaved in front of a little mirror while others practised military drills outside.

"It is calm today," said San Sanych. "But usually at about five or six o'clock in the afternoon the separatists start firing."