KIEV: Six Ukrainian troops were killed in two separate incidents in the troubled separatist-held east Sunday as isolated clashes continue to violate a fragile ceasefire to end the year-long war, officials said.

"Unfortunately, six Ukrainian soldiers have been killed on Sunday," army spokesman Oleksandr Motuzyanyk told AFP.

Four soldiers died when their vehicle came under missile fire while crossing a bridge near the separatist bastion of Lugansk.

Two others were killed when an anti-tank mine exploded a few kilometres outside the government-held southeastern port city of Mariupol, the spokesman added.

After a lull of several days in the deadly Ukraine conflict, the latest fatalities bring to nine the number of soldiers reported dead in 48 hours.

In the first such announcement since last Monday, the government on Saturday reported the deaths of three soldiers when a mine exploded a few kilometres from Donetsk, another separatist stronghold in the once thriving industrial east of the country.

Some 6,000 people have been killed since fighting broke out between pro-Russian separatists and the Ukrainian government a year ago.

A February ceasefire between the two sides is largely holding but skirmishes continue, notably around Donetsk and the port of Mariupol, Kiev's largest remaining stronghold in the southeast.

Kiev and the West accuse Russian President Vladimir Putin of supporting the insurgency with troops, tanks and heavy weapons — accusations he rejects.

