Ukraine crisis: Regional chief claims four Ukrainian soldiers have been killed as fighting erupts again in the east of the country

Renewed clashes follow the capture of two wounded men who claim to be serving soldiers in the Russian army

Pro-Russia militant fires his weapon in the eastern Ukrainian city of Luhansk. File photo (Getty Images)

Fighting has erupted between Ukrainian government forces and Russian-backed separatists in eastern Ukraine, with claims four Ukrainian servicemen have been killed.

Gennady Moskal, governor of Luhansk region on the border with Russia, said on his website that separatists opened fire on government positions with mortar and artillery near the village of Katerinovka.

"According to preliminary data, four Ukrainian servicemen have been killed and two others have been wounded, one of them seriously," Moskal said.

The fatalities could not immediately be confirmed by the military in Kiev.

Though a ceasefire was declared after peace talks in Minsk, Belarus, in February, skirmishes and violations have continued with a daily mounting casualty toll from fighting mostly north-west of the city of Donetsk and near the coastal town of Mariupol on the Sea of Azov.

Ukrainian President Petro Poroshenko said last week that 83 Ukrainian servicemen had been killed since the ceasefire theoretically came into force in February.

Since then, five Ukrainian servicemen were killed over the weekend alone. The separatists have not given any casualty figures.

The news follows the capture of two wounded men who say they are Russian soldiers on active duty in the rebellious east. Ukrainian authorities claim they are definitive proof that Russia is at war in Ukraine, but Moscow hotly denies this.

Representatives of Amnesty International and the Organisation for Security and Cooperation in Europe, which has shepherded the shaky ceasefire, visited the men and found them apparently in reasonable condition.

"I got professional medical aid, surgery. To my relatives, I want to say everything is fine with me, I'm alive and well," said one, who identified himself as Yevgeny Yerofeyev, a captain in the Russian army.

A man, whom the SBU Ukrainian security service allege to be one of two captured Russian soldiers, lies on a bed at the Kiev Millitary hospital (Getty Images)

One of the captured soldiers shielded his face while speaking briefly to reporters from his hospital bed (Getty Images)

"I'm missing my family and relatives so much," the other, Sergeant Alexander Alexandrov, told reporters who accompanied the international representatives.

In video statements posted by the Ukrainian Security Service, the men said they were taking part in a reconnaissance operation in the Luhansk region at the weekend when they were fired on, wounded and captured. Both say they were members of an army brigade based in the Russian city of Togliatti and had been deployed in Ukraine for more than a month.

Throughout the yearlong fighting in eastern Ukraine in which at least 6,100 people have died, Russia has consistently denied assertions from Kiev and the West that Moscow is providing soldiers and equipment to back up the pro-Russia rebels. The statements by Yerofeyev and Alexandrov directly challenge that denial.

"We're dealing with real soldiers of the armed forces of the Russian Federation," said Ukrainian Security Service spokesman Markiyan Lubkivskiy.

Both the Kremlin and the Russian Defense Ministry reject the assertion that Yerofeyev and Alexandrov are Russian soldiers. A Defense Ministry spokesman said that they were former soldiers; Moscow has said that any Russians fighting in Ukraine are there only as volunteers.

It remains unclear what measures Russia will take for the two hospitalised men. Lubkivskiy said: "We did not get any request from the Kremlin or the Russian Federation about captured soldiers.... For the moment, there is no question about a transfer [of the men to Russia]".

Amnesty International's Ukraine spokesman, Bogdan Ovcharuk, was quoted by the Interfax news agency as saying the two men have asked to see the Russian consul, but no consular visit has been reported.

AP/Reuters