The charge came one day after Kiev and rebel envoys agreed to halt live-fire exercises along the 500-kilometre (300-mile) front splitting eastern separatist territories from the rest of the West-leaning former Soviet state.
Monitors from the Organization for Security and Co-operation in Europe (OSCE) had welcomed that decision and a separate deal to prepare for the resumption of some de-mining operations as positive steps ‘towards normalisation’.
But the press office of Ukraine's self-proclaimed ‘anti-terrorist operation’ released footage purportedly showing the rebels firing Grad multiple rocket launchers against government army positions outside the insurgent stronghold of Donetsk.
‘The invaders brazenly violated the Minsk Agreements by applying the massive use of heavy weapons,’ the Ukrainian military said in a statement.
Ukraine uses the term ‘the invaders’ to imply the presence of active Russian forces in the separatist regions of Lugansk and Donetsk.
The Kremlin refutes the charges and admits only to some off-duty or vacationing Russian soldiers fighting alongside the rebels on their own volition.
A truce and political reconciliation pact signed in the Belarussian capital Minsk one year ago required both sides to pull back from the front large-calibre weapons such as the Grad systems alleged used on Thursday.
But the Minsk deal was also intended to end one of Europe's bloodiest crises since the Balkans wars of the 1990s by the end of 2015.
That deadline has passed with sporadic fighting still raging and Ukraine unable to approve a constitutional amendment that would grant rebel-run regions temporary autonomous status under which they could hold OSCE-monitored local polls.
Ukraine on Thursday reported the death of one government soldier in a sniper attack in the separatist province of Lugansk.
The Minsk deal that Russia and Ukraine had agreed to with the help of the leaders of Germany and France will be under discussion again when the four sides' foreign ministers meet in Paris later on Thursday.
The United Nations reported on Thursday that at least 9,160 people have died since separatist gunmen revolted against the pro-Western leadership that replaced Kiev's ousted Russian-backed president in February 2014.
The insurgents seized government buildings in several eastern cities in a coordinated April 2014 assault that Kiev and its Western allies accuse Russia of both plotting and backing -- a charge Moscow denies.
