Russia has warned the truce in eastern Ukraine is in “constant threat of breaking down” as the region endures its worst violence in months.
At the same time Petro Poroshenko, Ukraine’s president, said the country must prepare itself for a “full-scale invasion”.
Ukraine has long accused Russia of fermenting the violence in eastern Ukraine in order to undermine the country’s pro-Western government, and it has also claimed its neighbour has contributed thousands of troops to the war.
A surge in fighting between Moscow-backed rebels and government forces accounted for at least 24 deaths on Wednesday, with rebels saying 14 of their fighters had been killed along with five civilians. Kiev reported five of its servicemen had died and 39 were wounded in heavy clashes with rebel forces.
Russian foreign minister Sergei Lavrov warned the Minsk ceasefire agreement was now in jeopardy and laid the blame for the renewed fighting at the door of the Ukrainian government owing to its unwillingness to negotiate with the rebels, which Kiev regards as nothing more than Moscow-sponsored terrorists.
He added: “The February Minsk [ceasefire] agreements are constantly under threat of breaking down because of the actions of the Kiev authorities, trying to walk away from their obligations to foster direct dialogue with Donbass.”
A Kremlin spokesman, added to the criticism of Kiev saying “the Ukrainian side has taken steps to aggravate tensions”.
The war of words between Russian and Ukraine coupled with the bloody clashes in eastern Ukraine have increased fears that the Minsk agreement is now passed beyond the point of salvation and the region is once again embroiled in a war that has already claimed the lives of more than 6,000 since it began in April last year.
One Ukrainian soldier in the east wrote on his Facebook page that “vicious is fighting is going on along the entire 450-kilometre front” while a medic quoted by the Ukrainian press described the disputed towns of Krasnohorivka and Maryinka as “on fire”.
In an address to the Ukrainian parliament Mr Poroshenko stressed the seriousness of the situation.
“The military must be ready as much for a renewal of an offensive by the enemy in the Donbass as they are for a full-scale invasion along the whole length of the border with Russia,” he said. “We must be truly ready for this.
“There remains a colossal threat of resumption of large-scale fighting on the part of Russian terrorist groups,” he continued, adding that he now believed there were 9,000 Russian servicemen on Ukrainian territory.
Rebel leaders denied launching – or preparing – an offensive, saying their forces had only reacted to prevent a “genocide” of their people.
Expressing its alarm over the renewed fighting in Ukraine, the European Commission warned it could trigger a “new spiral of violence and suffering”. It added a call for all sides to respect the ceasefire and reminded Russia that any easing or tightening of economic sanctions against it were dependent on the success or failure of the truce.
The savaging of the truce agreement has underlined the failure so far to find a political solution to the problem of eastern Ukraine despite the professed will of Ukraine, the EU and Russia. It has also led to mounting Western suspicions that despite its public commitment to the peace process Moscow prefers the war to continue in order to place more pressure on Ukraine and to sap its failing economic strength.