Ukrainian army spokesman Andriy Lysenko said on Saturday that three soldiers had been killed and two wounded in the explosion.

He said the landmine had gone off near Avdiyivka, referring to a village not far from Donetsk, a stronghold of pro-Russian separatist rebels waging an insurgency against the government in Kyiv.

There were no further details on the incident, which occurred in the midst of a ceasefire aimed at ending the year-long war in eastern Ukraine.

They are the first deaths announced by the Kyiv government since Monday, when one soldier was reported to have been killed.

Altogether some 6,000 people have been killed since fighting broke out last year.

Ceasefire tenuous, but holding

A ceasefire agreed by the two sides is being largely observed, but there have been occasional clashes around Donetsk and Mariupol, a port that is the largest remaining government-held town in the region.

Lysenko said heavy weapons had been used against the army "at least five times" on Friday, despite the truce.

The rebels hold large swathes of territory

A spokesman for the Organization of Security and Cooperation in Europe, which is monitoring the ceasefire, admitted that it remained fragile.

"As long as guns continue to be fired, and as long as substantial amounts of heavy weaponry continue to be concentrated in offensive and defensive positions, achieving a comprehensive and sustainable ceasefire will be difficult," Michael Bociurkiw told a weekly briefing.

He also warned of increasing humanitarian problems in the east, owing to a lack of hospitals, water and schools.

West-Russia mistrust

Kyiv and many Western countries accuse Russia of supporting the rebels with arms and troops, with the US and the European Union imposing economic sanctions on Moscow over its alleged role in the conflict.

Moscow has always denied the charges, admitting only that some Russians may have volunteered to join the rebels in their struggle.

The insurgency in eastern Ukraine was sparked on April 6 last year, when pro-Russian activists stormed government offices in Donetsk and Luhansk in response to the ousting of Moscow-friendly President Viktor Yanukovych amid huge street protests calling for Ukraine to move politically toward Europe.

tj/rc (AFP, Reuters)