DONETSK, Ukraine (AFP) - Visiting a museum may be the last thing on the minds of hardened insurgents in east Ukraine, but a group of them turned up at one in Donetsk - only to make off with a World War II tank and two howitzers.

"They had written authorisation to take them away," said a bewildered guard from his sentry post outside the immense World War II museum in the insurgent-held city.

"They loaded them into a big truck. They took the tank that was least damaged. I think they're going to use them to fight," he said, refusing to give his name.

When an AFP journalist visited the museum on Friday there were still markings on the ground from where the separatist fighters had revved up their vintage loot and made off.

A father and son - the only visitors to the normally bustling complex - gaped on in disbelief.

"Can you believe it? They're even stealing museum exhibits now," the father said, before taking a picture of his son swinging from the gun turret of one of the remaining tanks.

This is not the first time that the rebels seem to have gone back to the past in their hunt for weapons in the brutal three-month conflict pitting them against Ukraine's military.

Earlier this month footage emerged on YouTube of them purportedly firing up a WWII Stalin tank on a pedastal where it had stood for decades as a monument in the town of Kostyantynivka.

But while some might mock the rebels for resorting to such tactics, the fighting on the ground remains deadly serious.

Fierce clashes continue around the two separatist bastions Donetsk and Lugansk.

Fourteen people have been killed around Donetsk and two around Lugansk in the past 24 hours, local officials said on Friday.

Ukraine's army said it had lost 13 soldiers.