One Ukrainian soldier has been killed in a flare-up of the conflict with Russian-backed rebels in country's east, the army said Saturday, one day before the country's presidential election.
Kiev's armed forces said in a statement that the situation had "escalated significantly" in the previous 24 hours, accusing rebels of using heavy weaponry banned by peace agreements.
The army added that four of its soldiers were wounded in large-calibre mortar and artillery attacks.
The rebel authorities did not announce any casualties on their side.
Since 2014, some 13,000 people have been killed in the war which erupted after a popular uprising ousted the pro-Kremlin president and Russia annexed Crimea.
Kiev and its Western backers accuse Russia of funnelling troops and arms across the border to fan the flames of the conflict.
Moscow has denied the claims despite overwhelming evidence to the contrary.
On Sunday, Ukraine is to hold presidential polls in which the current pro-Western leader Petro Poroshenko is seeking to be re-elected.
Both his main rivals -- unexpected poll-leader comedian Volodymyr Zelensky and former prime minister Yuliya Tymoshenko -- have also expressed largely pro-European views during the campaign.
None of the openly pro-Russia candidates are seen as serious contenders in the first-round vote on Sunday.