Ben Aris in Moscow -

Ukraine's President-elect Petro Poroshenko vowed on May 26 to retake control of the east of the country quickly and efficiently. However, just hours after his victory was announced, some of the bloodiest fighting between security forces and pro-Russian militia seen thus far erupted around the Donetsk airport.

Following Poroshenko's first round election win, separatists in Donetsk imposed martial law in the region. A major gun battle with the Ukrainian army was soon underway. 

Even more intense fighting took place around the Donetsk airport, after the militia forces took control of the facility in the morning. TV reporters were unable to get close to the airport, which billowed black smoke as planes and helicopters buzzed overhead. The sounds of mortar shells and heavy machine gun fire were continuous as the Ukrainian army battered the occupying separatist forces. 

Report on fighting for Donetsk airport

Airstrikes started after the separatists failed to comply with the army ultimatum to surrender, Vladislav Seleznyov, the head of the counter-terror operation said on his Facebook page, according to RT. Video footage showed helicopter gun ships and jets firing rockets.  

The body count is unclear but the Ukrainian army claimed on May 27 that 32 "terrorists" were killed, with most of them Chechens and Russian Cossacks. Other reports put the death toll as high as 100. By the end of the day the Ukrainian army had retaken control of the airport, but it remains unclear if the President-elect ordered the attack. 

YouTube video purports to show Ukrainian fighter plane firing rockets on the airport in Donetsk

"Peace in the country and peace in the east is my main priority," Poroshenko said as he appeared at a press conference after taking around 55% of the May 25 vote. He signaled that he would seek to bring a swift end to the Ukrainian Army's much-criticized campaign to drive out the armed pro-Russia separatists. "The anti-terrorist operation cannot and should not last two or three months," he insisted. "It should and will last hours." 

His words stand in stark contrast to the disintegrating situation in the east, although the momentum does look to be swinging increasingly to Kyiv's forces, and the pressure on the separatists is building. The leader of the self declared Lugansk people's republic reportedly declared war on the adjacent republic of Donetsk on May 26. 

Slavyansk also came under attack from the Ukrainian army with the least three people being killed according to reports. Footage from the city showed the result of a mortar attack on a residential area. Several bodies lay by the side of Paris cut down by flying shrapnel. Another man was slumped against the entrance to an apartment block, reportedly hit in the head by flying shrapnel during the start of the attack. The locals were clearly in shock: "Its terrible. People live here. They killed people. Oh my God, they killed them," wailed on resident referring to her neighbours lying dead on the path.

RT report on the shelling of Slavyansk (warning: graphic footage)

There was fighting in Mariupol, which has been the scene of several battles between the Ukrainian army and separatist forces in recent weeks. The Ukrainian army reportedly killed 5 pro-Russian insurgents and detained 3 others.