Ukraine on Wednesday reported the death of two soldiers and was blamed by pro-Russian rebels for killing a civilian in fighting that followed another failed round of EU-mediated peace talks.

The Kiev-appointed head of Lugansk -- an eastern province that along with its larger neighbour Donetsk have been waging a 15-month war against Ukraine's pro-Western leadership -- said three troops were also injured when their vehicle came under fire from insurgents.

"One soldier was seriously wounded and then died, and three more injured soldiers were hospitalised," Lugansk governor Gennadiy Moskal said in a statement.

Kiev's army reported the death of another serviceman in a separate incident in the devastated industrial heartland of the ex-Soviet state.

"The number of (rebel) attacks has doubled," Ukrainian military spokesman Oleksandr Motuzyanyk told reporters.

The Donetsk militants' news site said an elderly man had also died of his wounds after the regional town of Gorlivka came under attack from Ukrainian units.

The clashes -- sporadic since the start of the month -- resumed with renewed vigour in the wake of another round of unproductive talks Tuesday between Moscow and Kiev envoys that were also attended by the rebels in the Belarussian capital Minsk.

The Organization for Security and Co-operation in Europe (OSCE) said the latest meeting -- aimed at salvaging a February truce and political settlement agreement -- focused on pulling smaller-calibre weapons from a disputed demilitarised zone.

The two sides also disagree about the terms and timing of new local elections that the rebel-run districts want to hold within the next four months.

The insurgents called in a joint statement on Wednesday for the UN Security Council to create a tribunal that would investigate "war crimes" committed by government troops.

It is not the first time that proposal has been made and it is -- as on previous occasions -- likely to fall on deaf ears because of the conviction by Western powers that the war is being choreographed by Russia.

Western rights groups have accused both Ukrainian volunteer forces and separatist militia units of resorting to tactics such as abductions and torture.

Moscow denies either instigating the uprising or providing the militias with heavy weapons and tacit support from Russian troops.

But it provides the separatists with strong diplomatic backing at both the United Nations and the Minsk talks.

The seemingly-stalemated crisis has killed more than 6,500 people and reintroduced a Cold War-era chill in Moscow's relations with the West.