Kiev (AFP) - German Chancellor Angel Merkel and French President Francois Hollande took the rare step Friday of pressing Ukraine's Western-backed leader to ensure partial self-rule for the pro-Russian separatist east.

The blunt message from two of Ukrainian President Petro Poroshenko's most important allies marked another sign of European impatience with fighting that still engulfs the ex-Soviet nation five months after the signing of a broad truce.

The 13-point agreement reached in the Belarussian capital Minsk controversially guarantees three years of autonomy to militia-run districts of Ukraine's industrial provinces of Lugansk and Donetsk.

The mostly Russian-speaking regions -- dotted with war-shattered steel mills and coal mines that once fuelled Ukraine's economy -- want their special status spelled out in constitutional amendments that would be enormously difficult to overturn.

But Poroshenko's draft changes so far only make passing reference to an existing piece of legislation that gives insurgency leaders temporary self-administration rights.

The rebels fear the law could be easily watered-down or even revoked -- a decision that would cheer Ukraine's nationalist forces and outrage Russian President Vladimir Putin.

The European Union's dire state of relations with Russia have been of particular concern to Merkel as she tries to return calm to the continent's jittery markets and bring more stability to the 28-nation bloc's eastern front.

Poroshenko said Merkel and Hollande -- both present at the Minsk agreement's signing in February -- had "recommended that the president of Ukraine continue with (his) constitutional reforms".

The two "especially stressed that the draft constitution of Ukraine reflects special self-rule for certain districts of the Donetsk and Lugansk regions".

Hollande's office confirmed that the French leader and Merkel placed "particular emphasis on the special status of certain areas in the regions of Donetsk and Lugansk in the draft constitution".

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The German statement carried a similar message. None of the sides mentioned who had initiated the conference call.

- Terror and sabotage -

More than 6,500 people have died and 1.4 million have been left homeless since the conflict erupted in the wake of the February 2014 ouster of a Russian-backed leader and his replacement by a strongly pro-Western leadership.

The Minsk deal managed to contain some of the clashes but daily exchanges of fire still flare.

A Ukrainian military spokesman accused the insurgents Friday of "once again resorting to the use of heavy weapons, sabotage and reconnaissance groups".

Poroshenko also somewhat unexpectedly warned citizens Friday of the mounting threat of "terror" facing peaceful cities now under full Ukrainian control.

The 49-year-old former chocolate magnate said his efforts to stamp out the uprising had drained security resources and left swathes of Ukraine open to attacks from criminals and those allied to rebel fighters.

"The terrorist threat level has significantly risen outside the zone where we are conducting our anti-terrorist operation," Poroshenko said.

Ukraine refers to the insurgents as "terrorists" -- a label that infuriates Russia.

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

But it offers the separatists strong diplomatic backing at both the United Nations and the periodic Minsk truce talks.

Putin said Friday that Ukrainian peace efforts were "stalling" because of Poroshenko's refusal to hold direct talks with the self-declared leaders of Lugansk and Donetsk.

"Yet I still tend to think that (the truce) is more likely to succeed than fail," Putin said on the sidelines of a BRICS emerging nations summit in the Russian city of Ufa.