Ukrainian fighter jets and combat helicopters struck the terminal building at Donetsk airport to try to dislodge scores of separatist gunmen who seized the complex, triggering hours of heavy firefights. (Agencies)
It was the most forceful action by the Kiev government in its battle to crush a bloody pro-Moscow insurgency that has raged in the industrial east since early April, threatening to tear apart the former Soviet state.
The fighting flared on very day that Poroshenko – who has pledged to try to bring peace and unity after months of turmoil -- was formally declared the winner of yesterday's presidential election with 54 percent of the vote.
The Donetsk city mayor said there had been "civilian casualties" in the battles and told local residents to stay indoors.
Plumes of thick black smoke rose from the airport complex as the sound of explosions and heavy machinegun fire rang out throughout the day.
There was no confirmation of casualties but AFP correspondents saw the body of a woman near the Donetsk train station, although it was not clear how she died.
Scores of gunmen had stormed the airport in an apparent show of defiance against Poroshenko, underscoring the daunting challenges ahead to prevent the former Soviet state from plunging into all-out civil war.
Ukraine's election chief confirmed the billionaire chocolate baron president, saying his 41-point lead over closest rival, former prime minister Yulia Tymoshenko, was unassailable with only a tenth of the ballots left to count.
Even before the results, the 48-year-old Poroshenko had moved swiftly to stamp his authority as Ukraine's new leader, vowing to rebuild relations with Russia while steering the country on a westward path.
He said Ukraine would press on with its offensive against insurgents who now control about a dozen cities and towns in the east, and insisted there would be "no talks with terrorists".
Ukrainian fighter jets and combat helicopters struck the terminal building at Donetsk airport to try to dislodge scores of separatist gunmen who seized the complex, triggering hours of heavy firefights.