Russia's closest European ally, Hungarian Prime Minister Viktor Orban, has drawn ire from the EU over his Friday trip to meet Kremlin leader Vladimir Putin in Moscow.

Orban, whose country assumed the European Union's rotating presidency on July 1, is a self-declared "peacemaker" whose administration has repeatedly opposed — but mostly allowed to pass — EU and NATO military and financial aid measures in support of war-torn neighbor Ukraine.

Hungary has retained working relations with Russia despite most other Western countries completely cutting ties with the nation in response to its February 2022 invasion of Ukraine. Setting a landmark precedent, NATO last month agreed to allow Budapest's nonparticipation in the coalition's deepening support of Ukraine — in exchange for Hungary not blocking such initiatives.

Hungary will soon become the only country in Europe able to carry out dialogue with both Russia and Ukraine, Orban told Putin during the Friday visit, according to comments reported by Reuters and Russian state news agency Tass.

The trip to Moscow is the second stop on Orban's self-described "peace mission," after the Hungarian leader carried out his first wartime visit to Ukraine on Tuesday to meet President Volodymyr Zelenskyy.

After the engagement, Zelenskyy said that the pair had held talks over "the most fundamental issues of our neighborly relations – trade, cross-border cooperation, infrastructure, and energy," and noted that the dialogue could set the foundation for "a new bilateral document" between the two nations.

Orban also stressed Budapest's intentions to improve ties with Ukraine, while calling on Zelenskyy to consider a cease-fire in the hostilities with Russia in a bid to accelerate peace talks, Reuters reported.

"You cannot make peace from a comfortable armchair in Brussels," Orban said Friday in a social media post. "Even if the rotating EU-Presidency has no mandate to negotiate on behalf of the EU, we cannot sit back and wait for the war to miraculously end. We will serve as an important tool in making the first steps towards #peace. This is what our peace mission is about."

Several peace initiatives have been floated — including Zelenskyy's 10-point plan, a Chinese proposal and Putin's own conditions to entertain negotiations — without gaining traction.

The Ukrainian Foreign Ministry said Kyiv was not advised of Orban's trip to Moscow, which was made "without agreement or coordination with Ukraine," according to a Google-translated statement.

"We remind you that for our country the principle of 'no agreements on Ukraine without Ukraine' remains inviolable and we call on all countries to strictly adhere to it," the Ukrainian Foreign Ministry said, adding that the "only realistic way to restore a just peace" remains Zelenskyy's peace formula.

Orban's trip to Moscow has also drawn the wrath of European officials, who questioned his authority to represent the bloc.

EU chief diplomat Josep Borrell on Friday said the trip falls "exclusively, in the framework of the bilateral relations between Hungary and Russia," stressing that Orban does not represent the European bloc in this engagement.

Also referencing Orban's visit, European Commission President Ursula von der Leyen warned that "appeasement will not stop Putin. Only unity and determination will pave the path to a comprehensive, just and lasting peace in Ukraine."

Under the EU's guidelines, the bloc's rotating six-month presidency "chairs meetings at every level in the Council, helping to ensure the continuity of the EU's work in the Council."

Orban assumed the post earlier this week with a goal to "make Europe great again" — a tagline reminiscent of the 2016 campaign slogan of former U.S. President Donald Trump.