KIEV — President Petro Poroshenko said Monday that he is halting a unilateral cease-fire in Ukraine’s conflict with pro-Russian separatists, and said government forces will go on the offensive against the rebels.
Poroshenko announced his decision on his website, saying that ‘‘we will attack and we will free our country.’’
The shaky cease-fire expired Monday night. The idea was to give rebels a chance to disarm, and to start a broader peace process including an amnesty and new elections.
But rebels did not disarm, and the cease-fire was continually violated. Rebels did not comply with Poroshenko’s latest push to get them to turn over key border crossings with Russia, and permit international monitoring of the cease-fire.
‘‘The unique chance to put the peace plan into practice was not realized,’’ Poroshenko said in a speech prepared for delivery to the nation. ‘‘This happened because of the criminal actions of the fighters.’’
He had previously extended the cease-fire from seven days as part of a plan to end the fighting, which has killed more than 400 people since April.
Poroshenko’s decision followed four-way talks in search of a solution with Russia’s president, Vladimir Putin, Chancellor Angela Merkel of German, and President Francois Hollande of France on Monday as the deadline approached. He issued a statement after the talks ended saying the key conditions needed to continue the cease-fire had not been met.
European leaders and the United States have urged Russia to use its influence with the rebels to ease the bloodshed, and have threatened to impose another round of economic sanctions against Moscow.
While Putin has expressed support for the cease-fire, the West has accused Russia of allowing weapons and fighters to flow into Ukraine.
Poroshenko said he meant for a cease-fire to be followed by an amnesty for fighters who had not committed serious crimes, and political concessions such as early local and regional elections, protections for speakers of Russian, and, in the longer term, changes to the constitution to decentralize power to the regions.
French officials said Monday’s phone call touched on establishing a full cease-fire by both sides, having international monitors on the border between Russia and Ukraine, freeing prisoners, and holding substantial talks with the rebels.
Rebel leader Alexander Borodai on Monday welcomed having observers monitor the situation in the separatist region, but rejected the demand to hand back the checkpoints.
Stymied by the rebels’ refusal, Russia’s foreign minister, Sergey Lavrov, said Putin suggested to Poroshenko that both Ukrainian monitors and observers from the Organization for the Security and Cooperation in Europe deploy to checkpoints on the Russian side of the border to ensure ‘‘they aren’t used for illegal means.’’
White House spokesman Josh Earnest said the United States welcomes encouraging words from Putin but is looking for the Russian leader to take ‘‘tangible actions’’ rather than just issue positive sentiments to avoid additional sanctions.
‘‘We are still in a situation where those actions do not indicate a seriousness of purpose when it comes to deescalating the situation in Ukraine,’’ Earnest said. ‘‘That’s what leaves Russia at risk’’ of further sanctions.
Sporadic fighting flared early Monday despite the cease-fire. Shelling killed at least two people and ruined several apartments in the rebel-held city of Slovyansk, where shooting kept up through the night. Some of the shelling appeared to be directed at rebel positions, but other shells landed in a residential neighborhood.