The Kremlin warned Saturday that the assassination of east Ukraine's top separatist leader was a provocation that would undermine the long-stalled, Western-brokered peace deal and fuel tensions in the smouldering conflict.
Alexander Zakharchenko, the 42-year-old chief of the self-proclaimed Donetsk People's Republic, was killed in a bombing at a Donetsk cafe in broad daylight Friday, becoming the four-year conflict's most prominent victim from the Moscow-backed side.
His bodyguard also died and 12 more people were injured.
Moscow and rebel authorities have pointed the finger at Kiev while Ukraine links the bombing to internal feuding and Russia's desire to control the territory.
Officials led by President Vladimir Putin's spokesman said the former electrician's murder would further derail the Ukraine peace deal brokered by Germany and France in the Belarussian capital Minsk in 2015.
"This is no doubt a provocation," said Kremlin spokesman Dmitry Peskov.
"Zakharchenko's death will certainly lead to increased tensions in the region" and undermine conditions for the "start of the implementation" of the so-called Minsk agreements.
- 'Serious situation' -
Zakharchenko was a co-signee of the peace agreement, along with fellow rebel Igor Plotnitsky, the chief of the self-proclaimed Lugansk People's Republic, who was deposed in late 2017.
Germany and France have sought in recent months to revive the stalled peace process in a bid to end a conflict that has killed more than 10,000 since April 2014.
Russia's top diplomat Sergei Lavrov ruled out any meetings with France, Germany and Ukraine to discuss the crisis following the bombing.
"This is a serious situation that has to be analysed," Lavrov was quoted as saying by Russian news agencies.
There was no immediate reaction from Berlin or Paris.
A spokeswoman for the French foreign ministry told AFP it would not be providing a comment "at this stage".
Meanwhile, US special envoy for Ukraine Kurt Volker told The Guardian that Washington could increase arms supplies to Kiev to buttress the country's naval and air defence forces.
Volker made clear that the Trump administration was "absolutely" prepared to go further in supplying weaponry to Ukraine than anti-tank missiles it delivered in April, The Guardian said.
Putin on Friday swiftly sent condolences and seemed to imply that Kiev may be behind the murder.
"Those who have chosen the path of terror, violence and intimidation do not want to look for a peaceful, political settlement of the conflict, do not want to have genuine dialogue with residents of the southeast," Putin said.
But some in Ukraine and Russia allege Moscow could be behind Zakharchenko's demise.
"A systematic purge is under way of all those who helped bring Russian troops into the Donbass and helped create the pseudo-people's republics," the head of Ukraine's security service Vasyl Grytsak said, referring to war-torn eastern Ukraine.
Other top figures who have been killed outside the battlefield include commanders Alexei Mozgovoy and Arsen Pavlov better known by his nom de guerre Motorola.
In east Ukraine, senior separatist commander Eduard Basurin claimed Kiev planned to launch an offensive in mid-September, adding separatist troops had been put on high alert. Kiev has denied any such plans.
Rebel authorities in Donetsk declared a three-day period of mourning and delayed the start of a new school year until Tuesday.
The acting head of the region, Dmitry Trapeznikov, said authorities had detained several suspects and they helped confirm that the blast was "an act of sabotage by Ukraine".
- 'Tragedy for entire Donbass' -
People in Donetsk openly wept at the news of Zakharchenko's death.
"It is a tragedy for the entire Donbass," said Donetsk resident, Alexander Grigoryev, 61.
"It's such a pity. He could have been the leader of our country for a very long time," he said.
Zakharchenko had led Russian-backed insurgents in the rebel region for the last four years.
In November 2014, he was elected the first president of the Donetsk republic, facing no real opposition.
Zakharchenko, who liked to be seen wearing khaki military fatigues, sold his business to finance the rebels and took part in the storming of the Donetsk regional administration building that launched the conflict in 2014.