Ukraine's leader warned on Tuesday that a war with pro-Russian separatists could still break out again as its military said the rebels had greatly stepped up attacks and widened the area of their operations despite a ceasefire.
A military spokesman said one Ukrainian serviceman had been killed -- the fourth fatality among the Ukrainian armed forces in four successive days -- and 14 others wounded in a surge in violence at flashpoints in Ukraine's east and south-east.
The latest violence has revived concerns that a peace deal, brokered in Minsk, Belarus, by the leaders of Ukraine, Russia, Germany and France, in February could collapse. Both sides accuse each other of violations.
Speaking at a conference called to reassure Ukraine's Western backers that Kiev would stick to reforms to earn a place in mainstream Europe, President Petro Poroshenko said Kiev saw no other solution to the conflict in the east other than by negotiations and diplomacy.
But he added: "We are still under a threat of war."
More than 6,100 civilians, separatists and military personnel have been killed so far in the conflict. Fighting erupted in Ukraine's Russian-speaking east after the Moscow-backed president was ousted in a public revolt and Russia annexed Crimea.
"In the past 24 hours the resistance (from separatists) has significantly increased. The geographical area of ceasefire violations by the separatists has widened," military spokesman Oleksander Motuzyanyk told journalists.
Attacks had been intense around Shyrokyne, east of the coastal city of Mariupol on the Sea of Azov, he said. Motuzyanyk also alleged that rebels were using large-caliber weapons and grad rocket systems in violation of the February ceasefire.
Near Donetsk, a big city now under rebel control, separatists were trying to probe Ukrainian government defenses at Avdiyivka, a coke-producing center and the northern gateway to the city, he said.
"The increase in the quantity of armed attacks ... demonstrate the unwillingness of the separatists to settle the conflict by peaceful means," Motuzyanyk said.
Speaking to journalists at the conference in Kiev, Prime Minister Arseny Yatseniuk said: "It has to be clearly stated: attracting a private investor to a country which is at war with a nuclear-armed state - the Russian Federation - is very difficult."
From Belgrade, German Frank-Walter Steinmeier called on both rebels and the Ukrainian government "not to risk the Minsk peace agreement."
"The process of implementation (of the Minsk agreement) must be accelerated ... unfortunately over recent days we have backtracked in terms of the conflict intensifying," he said.
