Ukraine's Western-backed president has decided to resume a military offensive against pro-Russian separatists in the country's restive east after opting not to prolong a shaky truce, a move that threatens to escalate the deadly conflict.
"After examining the situation I have decided, as commander-in-chief of the armed forces, not to extend the unilateral ceasefire," Petro Poroshenko said in an address to the nation late Monday.
"We will attack," the newly-elected leader said.
The announcement could trigger a steep escalation in the months-long conflict after a diplomatic push led by France and Germany failed to convince Kiev to extend a 10-day truce that did not quell the fighting in the rebellious eastern regions.  
But Poroshenko -- under pressure from the Ukrainian public to toughen his stance on the uprising -- insisted that Kiev was not abandoning its peace plan altogether.
"We are even ready to return to a ceasefire at any moment. When we see that all the parties agree to enact the essential points of the peace plan," he said.
Ukraine and its Western allies accuse Moscow of fuelling the bloodshed that has claimed some 450 lives by sending arms and fighters across the porous border between the two ex-Soviet neighbours.
The Ukrainian president's announcement came a few hours after a conference call with the leaders of Russia, France and Germany, who were pushing for the ceasefire to be extended.
The French presidency had said that Kiev and Moscow were working on the "adoption of an agreement on a bilateral ceasefire," sparking expectations that the truce would continue.  
But Kiev said only that all sides agreed that a new bilateral ceasefire should be discussed at a fresh round of "consultations" involving an OSCE envoy, a Russian diplomat and former Ukrainian leader Leonid Kuchma.
For its part, the Kremlin backed new indirect talks and said Putin had "stressed the importance of extending a ceasefire", to be monitored by international observers.
Prior to Monday's teleconference -- the second in two days between the four leaders -- French President Francois Hollande and German Chancellor Angela Merkel reiterated a European Union warning of more sanctions against Moscow unless the Kremlin explicitly pressured pro-Kremlin rebels to stop fighting.
Broader sanctions could cut off whole sectors of the Russian economy from the EU's 500 million consumers, pushing it into recession with the International Monetary Fund already warning of negligible growth.
There was no immediate reaction from the separatists but the Interfax-Ukraine news agency cited unnamed insurgent commanders as saying that shelling had started in the rebel-held town of Kramatorsk.
In the talks between the four leaders some headway appeared to be made on the contentious issue of shoring up Ukraine's porous border with Russia, through which Kiev accuses Moscow of sending fighters and weapons.
President Vladimir Putin was "ready to authorise Ukrainian border guards access to Russian territory" to help monitor the leaky frontier, Steffen Seibert, a spokesman for Merkel said.
- Ceasefire has little impact -
On the ground the 10 days of supposed truce has done little to stem the violence with both sides accusing each other of carrying on firing.
On Monday Russian state TV station Channel One said that its cameraman Anatoly Klyan, 68, died after being shot in the stomach by Ukrainian troops while on an overnight reporting trip with insurgents at a military base near the rebel-controlled city of Donetsk.    
Russia's foreign ministry said the death showed that Ukrainian forces "clearly do not want a de-escalation in the armed conflict in the east."
Meanwhile, Ukrainian authorities have claimed that some 27 servicemen were killed during the ceasefire and almost 70 injured, local media reported.  
Poroshenko has been coming under growing public pressure to launch a full-scale assault, with some 500 people protesting against the ceasefire outside his office on Sunday.    
The Ukrainian leader refuses to meet rebel commanders who have "blood on their hands" and on Monday criticised their "the flagrant way they violated the ceasefire".
Separatist chiefs say they will not engage in direct negotiations with Kiev until government forces withdraw from the heavily Russified east.
Over the past few days the rebels have tightened their grip in the region by forcing a string of pro-government military bases around Donetsk to surrender.
Last week Poroshenko put his name to a historic trade deal with Europe that ruptured Kiev's historic ties with Moscow.
Kiev and its Western allies accuse Russia of both arming and funding the militias in a bid to unsettle the new Ukrainian government as revenge for the February ouster of a pro-Kremlin president who had ditched the very EU agreement Poroshenko signed on Friday.
Russian and EU ministers have tentatively agreed to meet on July 11 to discuss Moscow's concerns over the EU agreement with Kiev.