At least six Ukrainian servicemen have been killed in rebel attacks in Ukraine's troubled eastern regions in a grim weekend marking the first anniversary of a rebellion against the country's pro-Western rulers.

After weeks in which a shaky ceasefire deal appeared to be largely holding despite isolated clashes, the fatalities brought to nine the number of soldiers reported dead within just 48 hours.

Four soldiers died on Sunday when their vehicle was hit by a shell fired by the Russian-backed rebels as it drove across a bridge in the government-held town of Schastye, 170km north-east of the big regional centre of Donetsk, regional police said.

In a separate incident less than an hour later, a landmine exploded under a military vehicle at Shyrokyne, east of the Sea of Azov city of Mariupol, killing two soldiers and injuring a third, a military spokesman said on the TV channel 112.

The new casualties, which followed the deaths of three Ukrainian servicemen in a landmine explosion on Saturday, put further strain on a tenuous ceasefire struck two months ago in the Belarusian capital Minsk.

The conflict erupted a year ago this weekend when rebels opposed to a new pro-Western leadership in Kiev and the ousting of a Moscow-backed president occupied state buildings in two big cities of Ukraine's Russian-speaking east, Donetsk and Luhansk.

Stalemate

More than 6,000 civilians, rebels and Ukrainian servicemen have been killed since then in a crisis in which Kiev has accused its former Soviet master of arming and supporting the rebels and the West - backing Ukraine - has brought economic and financial sanctions against Russia.

The crisis has now reached stalemate with a ceasefire, brokered by Ukraine, Russia, Germany and France in mid-February still technically in force though deaths are reported almost daily among Ukrainian soldiers, civilians and rebels.

However, large swathes of the industrialised east, including the cities of Donetsk and Luhansk, are under the control of the rebels and Kiev fears they could be preparing to try to take Mariupol, a city of half a million people.

Under an agreement reached in September 2014 and renewed in February, the warring sides have pulled back heavy military equipment to put their big guns out of range of each other and are working on extending the withdrawal to include tanks and smaller-calibre weapons.

The status of the separatist-minded regions, whose leaders have proclaimed 'people's republics', remains disputed, and the rebels appear unlikely to allow Ukrainian elections to be held there later this year.

Both sides accuse each other of violating the ceasefire agreed in Minsk despite the pull-back of heavy weapons.

Source: Agencies