The Ukrainian army has inflicted serious damage on Russia's armed forces, despite the fall of the key port city of Mariupol, President Volodymyr Zelenskyy said Saturday.

Ukraine has "broken the backbone" of the Russian army, Zelenskyy claimed in a television interview. "They will not be able to get back on their feet for the next few years," he added.

His comments came after the last 2,400 fighters of Mariupol surrendered and were taken captive.

Kyiv will take it all back, he adamantly said, adding that Ukraine would see a return to the front lines before Feb. 24, when Russia invaded, a victory.

"It will mean that they did not conquer us and that we defended our country," he said, though he noted this would be very difficult and that diplomacy would follow.

Meanwhile, Zelenskyy also said Ukraine needs to become a full candidate to join the European Union, rather than signing up to the kind of broader "European political community" antechamber proposed by France.

"We don't need any alternatives to the application of Ukraine to join the EU, we don't need such compromises," Zelenskyy told reporters in Kyiv during a joint press conference with visiting Portuguese Prime Minister Antonio Costa.

French President Emmanuel Macron raised hackles in Ukraine on May 9 by suggesting that the country could take "decades" to become a full EU member and should aspire instead to join a "European political community," a sort of antechamber for the EU.

Ukraine would notably have to meet rigorous standards in governance, fight corruption and apply the rule of law before it could be admitted as an EU member.

Russia invaded Ukraine in February, in part to thwart Kyiv's tilt toward integration with the EU and NATO.

But Zelenskyy was adamant on Saturday that his country should be allowed to start the process toward full EU membership.

"Because, believe me, it will not be compromised with Ukraine in Europe, it will be another compromise between Europe and Russia. I am absolutely sure of that," he said.

"This is the influence and political and diplomatic pressure of Russian officials and lobbyists on the decision of a European country to support Ukraine or not," he continued.

Macron's "European political community" initiative will be debated at an EU summit in late June. The French leader has suggested that Britain, which left the EU after a referendum, could also join such a grouping.

But some European leaders have already criticized the idea.

"My impression is that this is an attempt to cover up the obvious lack of political will to take decisive decisions on granting candidate status," Lithuanian President Gitanas Nauseda said last week.

On Friday, British Foreign Secretary Liz Truss also poured cold water on Macron's idea.

"My preference is to build on the structures we already have that work successfully, whether it is the G-7 or NATO," she said.