Gergely Gulyás, Head of the Prime Minister's Office, said that if Europe allows Ukraine to become an EU member once the war is over, "it could cost more than the war itself".
Gulyás told a conference in Budapest on Thursday that in peacetime, Ukraine's accession could "pose the greatest danger" to the bloc.
He said it was a welcome development that "now Europe is talking more and more about the need for peace", adding that "peace offers the best opportunities for Hungary's economic growth".
Gulyás said the worst-case scenario would be "the wrong peace or no peace", but added that "if Ukraine's accession continues to be Brussels' goal, it would put an even greater burden on the community than the war itself".
Meanwhile, Gulyás said Hungary's employment figures were "among the highest in Europe" despite war-related difficulties, adding that "one million people more are working in Hungary than in 2010".
"The government's goals are clear: the family support system needs to be expanded, while small and medium-sized companies need to be helped," Gulyás said. Integrating the Roma minority into the workforce through education and labour programmes is a key government task, he added.