DONETSK, Ukraine — Discouraged but defiant, pro-Russia separatists vowed to keep fighting the government in Kiev from the largest city in eastern Ukraine, where they regrouped Sunday after being driven out of a key stronghold.
At a rally in a central Donetsk square, the rebels were cheered on by thousands of supporters waving flags from Russia and the self-proclaimed independent Donetsk People’s Republic. Many urged President Vladimir Putin of Russia to quickly come to their aid, but there was no comment Sunday from Russia.
Although the rebel withdrawal Saturday from Slovyansk, a city of 100,000 they had held for months, was not a total victory, President Petro Poroshenko said purging the city of the insurgents had ‘‘incredible symbolic importance.’’
It was unclear whether the government — after abandoning a cease-fire last week and going back on the offensive — was now winning the fight that had sputtered for months.
Rebel fighters from Slovyansk could be seen walking through Donetsk on Sunday in groups of 10 to 15.
Most were still wearing camouflage, but some sported identical new bright-colored shorts and shirts. It was an unsuccessful effort to blend in with the civilian population, since they still carried automatic weapons.
At one money-exchange office in the city center, about 20 rebels lined up to trade US dollars for Ukrainian hryvnas. The dollar is considered a more stable currency in Ukraine and Russia, but it was not known who had given them to the rebels. They refused to speak with a reporter.
Igor Girkin, defense minister of what the separatists call the Donetsk People’s Republic, told the Russian television channel Life News on Sunday that he would coordinate the fight from Donetsk.
‘‘We will continue the combat operations and will try not to make the same mistakes that we made in the past,’’ said Girkin, a Russian also known by his nom de guerre, Igor Strelkov. Ukrainian authorities have identified him as a veteran of the Russian military intelligence agency.
Rhetoric soared Sunday afternoon at the rally.
‘‘We will begin a real partisan war around the whole perimeter of Donetsk,’’ Pavel Gubarev, the self-described governor of the Donetsk People’s Republic, told the crowd. ‘‘We will drown these wretches in blood.’’
But he said the insurgents could easily die in Donetsk if Russia did not do more to help them. Gubarev said rebels were forced to flee Slovyansk because several commanders had betrayed Girkin and left his forces there vulnerable to attack.