Kiev: Kiev on Thursday said two soldiers had been killed in the heaviest clashes since the signing of a February truce deal with pro-Russian insurgents in Ukraine`s separatist east.
Ukrainian National Security and Defence Council Secretary Oleksandr Turchynov said militants had shelled government positions 153 times across the war zone.
Turchynov called the number "an anti-record" that marked the most serious escalation since the signing of the so-called Minsk II accord.
"In essence, shelling this intense corresponds to active hostilities," he said in a statement, which echoed similar remarks by other military officials since the weekend.
Kiev`s pro-Western forces have been fighting the militias for control of a vital highway linking the government-held southeastern port of Mariupol with the separatists` de facto capital Donetsk to the north.
Most of the road is currently overseen by pro-Kiev units. If the insurgents captured it, it could potentially allow them to step up their stop-start campaign to capture Mariupol -- a port city of nearly half a million that sits on the western edge of the loosely-defined demilitarisation zone.
The industrial port exports most of the east`s factory output and provides a land bridge between rebel territories and the Russian-occupied Crimea peninsula.
On their official news site, the separatists said Kiev shells had killed one civilian and injured three in an attack on Donetsk city itself.
They accused government forces of "firing 500 shells and rockets" at rebel positions in the Russian-speaking provinces of Lugansk and Donetsk.
The United Nations estimates that the conflict -- sparked by the February 2014 ouster of a Moscow-backed leadership and the rise of President Petro Poroshenko -- has killed more than 6,800 people and driven 1.4 million from their homes.
Repeated efforts to stop the 16-month conflict have been frustrated by some units` refusal to listen to their political commanders and the high level of mistrust between Moscow and Kiev.
Russia denies accusations by Ukraine and its allies of orchestrating and supporting the conflict to try to prevent Ukraine from joining the European Union and possibly NATO at a later date.
Minsk II was sealed only after all-night talks between Russian President Vladimir Putin and Poroshenko.
The pact offered the rebels broader autonomy but required them to cede control of their parts of the Russian-Ukrainian border to Kiev`s troops.
All of its terms had to be implemented by the end of the year -- a deadline that the two chief negotiators for the separatists said on Wednesday should be extended until the start of 2017.