The display of military might violated the terms of a long-ignored 2015 peace deal.
The display of military might used by the Moscow-backed insurgents in their three-year conflict against government forces violated the terms of a long-ignored 2015 peace deal.
Donetsk straddles a demarcation line in the industrial east of Ukraine from which both sides' big guns were meant to have been withdrawn almost two years ago.
An AFP reporter counted 45 pieces of heavy military equipment -- ranging from a lone World War II-era tank to its modern versions used in the current war as well as rocket launchers and anti-aircraft guns -- roll through the city's main street.
Donetsk separatist leader Alexander Zakharchenko led a march of about 1,000 fighters who held up a long banner painted the black and orange colours of Russia's patriotic Saint George's ribbon.
Others in the parade carried portraits of warlords killed in Europe's only war, in which more than 10,000 people have died.
Zakharchenko told the crowd that May 9 "is the holiest day for us all".
On the other side of the frontline Ukrainian authorities have joined European nations in marking the end of World War II on May 8 after its 2014 pro-EU revolution.
The decision was meant to underscore Ukraine's split with Russia and embrace of the West.
Ukrainian President Petro Poroshenko told a group of soldiers on Tuesday that "we will no longer celebrate this holiday along the Russian scenario."
But several hundred people carrying photographs of relatives who fought in what the Soviet Union called "The Great Patriotic War" still marched through Kiev on Tuesday.
They were confronted by a small group of nationalists who pelted them with several smoke bombs before being restrained by the police.
The atmosphere was calmer on Donetsk’s central Lenin Square.
Entire families watched the hardware roll by and cheered. Some parents dressed up their children in military fatigues.
Lenin Square itself was adorned by a 1960s L-29 Delfin military jet trainer used during the Cold War by nations in central and eastern Europe that were under the Kremlin's thumb.
A young student came to the rebel parade with a Russian Saint George's ribbon pinned to his shirt and a bouquet of flowers.
"I want to see the day when, at the end of our own war, we also get a chance to celebrate Victory Day," the 20-year-old told AFP.
"Our war is almost as long as the Great Patriotic War. It is time to finish it already."