KYIV, UKRAINE -- The owner of Russia's Wagner military contractor threatened Friday to withdraw his troops next week from the protracted battle for the eastern Ukrainian city of Bakhmut, accusing Moscow's military command of starving his forces of ammunition and causing them heavy losses.

Yevgeny Prigozhin, a wealthy entrepreneur with longtime links to Russian President Vladimir Putin, claimed that Wagner had planned to capture Bakhmut by May 9, Russia's major Victory Day holiday celebrating the defeat of Nazi Germany in the Second World War.

It is not the first time Prigozhin has raged about ammunition shortages and blamed Russia's military, with which he has long been in conflict. Known for his bluster, he has previously made unverifiable claims and threats he hasn't carried out.

Prigozhin's spokespeople also published a video of him Friday standing in front of about 30 uniformed bodies lying on the ground and saying they are Wagner fighters who died on Thursday alone. He angrily demands ammunition from Russian Defence Minister Sergei Shoigu and General Staff Chief Valery Gerasimov.

"These are someone's fathers and someone's sons," Prigozhin says, pointing at the bodies and swearing. "The scum that doesn't give us ammunition will eat their guts in hell."

Wagner has spearheaded the struggle for control of Bakhmut, the longest -- and likely bloodiest -- battle of the war. More than eight months of fighting there is believed to have cost thousands of lives. A pullout by Wagner would be a huge blow to the Russian campaign.

For the Ukrainian side, Bakhmut has become an important symbol of resistance to Russia's invasion. President Volodymyr Zelenskyy says its loss could begin building international support for a deal that could require Ukraine to make unacceptable compromises.

Prigozhin's spat with the Russian military leadership dates back to Wagner's creation less than 10 years ago. During the war in Ukraine, he has chastised Russia's top military officials, publicly accusing them of incompetence -- behavior that is highly unusual in Russia's tightly controlled political system.

One general Prigozhin actively criticized was fired, but other top officials he has lashed out at appear to have retained the Kremlin's trust. In January, Putin put Gerasimov in charge of the Russian forces in Ukraine, a move some observers also interpreted as an attempt to cut Prigozhin down to size.

Prigozhin alleged Friday that Russia's regular army was supposed to protect the flanks as Wagner troops pushed forward but is "barely holding on to them," deploying "tens and rarely hundreds" of troops.

Russia's Defence Ministry did not immediately comment on the claims, and it was not possible to independently verify them.

"Wagner ran out of resources to advance in early April, but we're advancing despite the fact that the enemy's resources outnumber ours fivefold," Prigozhin's statement said. "Because of the lack of ammunition, our losses are growing exponentially every day."

Ukrainian officials were skeptical about Prigozhin's claims of ammunition shortages. Ukraine's military intelligence representative, Andrii Cherniak, told The Associated Press that Wagner's forces had clearly failed in their goal of taking Bakhmut by May 9 and Prigozhin had made the statement to "justify their unsuccessful actions."

Prigozhin has toured Russian prisons to recruit fighters, promising inmates pardons if they survive a half-year tour of front-line duty with Wagner. Western countries and United Nations experts have accused Wagner mercenaries of committing numerous human rights abuses throughout Africa, including in the Central African Republic, Libya and Mali.

Bakhmut, located about 55 kilometres (34 miles) north of the Russian-held regional capital of Donetsk, has tactical military value for Moscow, though analysts say it won't be decisive in the war's outcome.

The city had a prewar population of 80,000 and was an important industrial centre. It is now a devastated ghost town.

Prigozhin's statement said Wagner will be forced to pull out of Bakhmut on May 10 and have Russia's regular army take over. He said his force hasn't received enough artillery ammunition supplies from the Russian military since Monday, and blamed "jealous military bureaucrats."

Western officials and analysts believe Russia has run low on ammunition as the 14-month conflict became bogged down in a war of attrition over the winter, with both sides resorting to long-range bombardments.

Prigozhin has already threatened to withdraw from Bakhmut once, in an interview with a Russian military blogger last week, if the situation with ammunition doesn't improve.

Asked by The AP about Prigozhin's statement, Kremlin spokesman Dmitry Peskov said during his daily conference call with reporters that he had seen refences to it in the media but refused to comment further.

Also Friday, an oil refinery in Russia's southern Krasnodar region which borders the annexed Crimean Peninsula briefly caught fire after it was attacked by a drone, Russia's state news agency Tass reported, citing emergency officials. The fire was small and was quickly put out, the report said.

It was the second straight day that the Ilyinsky refinery had came under a drone attack. Drone attacks on oil facilities in Russian regions on the border with Ukraine have been reported almost daily over the past week.