Ukrainian President Petro Poroshenko said he is halting a unilateral cease-fire in the conflict with pro-Russian separatists and says Ukrainian forces will go on the offensive against the rebels.
A statement from Poroshenko on his website early Tuesday said the cease-fire is being halted and that "we will attack and we will free our country."
"The unique chance to put the peace plan into practice was not realized," Poroshenko said. "This happened because of the criminal actions of the fighters."
Petroshenko's cease-fire, part of his plan to end a pro-Russia insurgency in the east, had expired at 10 p.m. local time (3 p.m. EST) on Monday.
The president had already once extended the laying down of arms last week from seven to 10 days. The cease-fire was called to give rebels a chance to disarm and to start a broader peace process including amnesty and new elections.
But it was seen as fragile at best throughout its existence, punctuated by sporadic fighting. Overnight, the shooting death of a Russian journalist underlined ongoing tensions in the restive east. The conflict overall has killed more than 400 people.
Ukraine has said that rebels continued to launch attacks, and Poroshenko faced protests in the country’s capital demanding tougher action against the separatists. The conditions for peace being pushed by Kiev include the return of control points on the border with Russia to Ukraine.
Poroshenko tried to keep his peace plan on track in a four-way phone call Sunday with Russian President Vladimir Putin and the leaders of France and Germany.
European leaders have previously pressed Russia to help de-escalate the situation or face the possibility of additional economic sanctions.
The two-hour conversation came ahead of a Monday deadline that European Union leaders set for Russia and the separatists to take steps to ease the violence, warning that otherwise they were ready "at any time" to impose further punitive measures.
German Chancellor Angela Merkel and French President Francois Hollande encouraged the Ukrainian and Russian presidents to work on meeting the EU conditions, Hollande's office said in a statement.
The EU's demands included the return of three border checkpoints to Ukrainian control, verification of the cease-fire by monitors from the Organization for Security and Cooperation in Europe, and talks to put Poroshenko's peace plan in place.
A previous statement issued by Poroshenko's office had underlined Ukraine's willingness to maintain the cease-fire at least until Monday evening, but expressed concern about the situation, noting what he said were multiple violations of the truce by separatist fighters. Poroshenko called on Putin to strengthen border controls from the Russian side to stop what Ukraine says is the flow of weapons, fighters and mercenaries.
Putin has expressed support for the cease-fire and Moscow has said that any Russians there have gone as private citizens.
Tension between Russia and Ukraine escalated in February when protests by people who wanted closer ties with the European Union drove pro-Russian president Viktor Yanukovych from office. Russia called that an illegal coup and seized Ukraine's Crimea region, saying it was protecting the rights of people there who speak Russian as their main language.
Al Jazeera and wire services