The traffic control tower of Donetsk Sergey Prokofiev International Airport is seen through a smoke during fighting between pro-Russian rebels and Ukrainian government forces in Donetsk.

AFP/Donetsk

Ukrainian forces clashed with pro-Russian insurgents yesterday over control of a strategic airport in the restive east and traded blame over the death of a Swiss aid worker, four weeks into their shaky truce.

Heavy fighting engulfed the flashpoint transport hub north of Donetsk, with blasts echoing across the largest rebel-held city throughout the day, but its status remained in dispute.

Separatist fighters said they were in control of almost the entire facility, which includes an old terminal and a brand new one built at a cost of nearly $1bn for the 2012 football European Championship.

The Ukrainian military confirmed that gunmen had briefly seized the first floor of the old building, but said they had since been pushed out, even though fighting continued.

The weeks-long battle for the prized but no longer operating airport, whose long runway could let the separatists land large planes, has been one of many violations of a Russia-backed ceasefire signed on September 5.

Since then, 71 Ukrainian soldiers and civilians – and an undisclosed number of separatists – have been killed across the Russian-speaking rustbelt, including a staff member of the Red Cross, whose office in Donetsk was hit on Thursday.

Both Moscow and the separatist command pinned the blame on Ukrainian forces, which in turn accused the insurgents.

Both sides have pelted Donetsk with long-range missiles that were developed in the Soviet era and are notoriously imprecise.

The five-month conflict has killed more than 3,200 people and despite repeated violations of the truce, Western leaders still view it as the only viable option for ending Europe’s worst crisis in decades.

Pro-Western President Petro Poroshenko assured the weary nation yesterday that he had “enough energy to stop this war”, adding that “the enemy has made us stronger” despite the loss of 946 Ukrainian soldiers and volunteers since the start of hostilities in April.

In Donetsk, a half-deserted city that once had nearly 1mn residents and is all but completely controlled by the self-proclaimed “Donetsk People’s Republic”, Kiev’s forces seemed to be hanging on by a thread after spending weeks holed up at the airport.

Separatist “prime minister” Alexander Zakharchenko told Russia’s RIA Novosti news agency that his men controlled 95% of the sprawling structure – all but one building.

A female rebel at a checkpoint 2km east of the airport told AFP that clashes around the field had gone uninterrupted since 7am.

“We are controlling the main part of the airport, the Ukrainians are still in one building,” she said.

“They (the Ukrainians) still hold two bunkers, we are fighting to take those,” said another rebel.

The Ukrainian military argued yesterday evening that its forces had repelled the attacks and were still “in control”, also accusing Russia of supplying the militias with reinforcements.

“Our reconnaissance observed the arrival of considerable armour, heavy artillery and soldiers into this area,” defence spokesman Andriy Lysenko said. “Russian forces have moved a unit of unmanned aerial vehicles to the airport area for reconnaissance, which are operated by Russian specialists.”

Kiev and the rebels, who agreed on September 19 to withdraw heavy weapons from a 30km buffer zone along the eastern front line, have blamed each other for violating the deal.

Lysenko said that the fighters’ failure to halt fire meant “the Ukrainian side was not withdrawing its weapons and continuing to defend its position”.

Kiev has blamed the recent deaths in central Donetsk on rebel attempts to discredit the army, while the militias accused the Ukrainian military of hitting residential areas by using indiscriminate fire.

UN Secretary General Ban Ki-moon said he was “saddened and disturbed” by the Swiss aid worker’s death, and the outgoing EU foreign affairs chief Catherine Ashton called on all parties to ensure open access for aid workers.