MEPs have criticised Hungarian Prime Minister Viktor Orban's meeting with Vladimir Putin on Tuesday, saying it risks EU unity over the Ukraine crisis.
Orban says he is travelling to more Moscow to increase natural gas supplies amid Europe's energy price hikes.
"Viktor Orbán is undermining joint decisions in Brussels by continuing to veto them," said Hungarian MEP Márton Gyöngyösi.
"In the world of diplomacy, the date and place of a high-level meeting, sometimes even the mere fact, has a very important message value," he added.
According to the European lawmaker, the fact that Orban is not negotiating and developing a strategy to defend NATO and the EU during this period, but is negotiating with Russia, is "roughly rubbing against a qualified case of treason".
But Orban says the talks in the Russian capital are necessary to get more cheap gas from Russia.
"I would like to establish during these talks that in this difficult period with energy price hikes, we can enlarge the natural gas quantity that has been agreed in Russian-Hungarian relations," Orbán said.
Last week, EU foreign ministers sent a warning to President Putin that Russia will face economic sanctions if it attacks Ukraine. As a sign of support, the European Parliament has sent a delegation to Kyiv, with French MEP Nathalie Loiseau warning Orbán he should not jeopardise EU unity.
"We have no doubt, Vladimir Putin is trying to divide us. So I sincerely hope that Viktor Orbán realises what is at stake and that he will stick to the message of unity of the European Union," Loiseau said.
But György Ilyas from the government-funded organisation in Budapest, the Institute of Foreign Affairs and Trade, played down the risk of Orban’s visit to Moscow.
"I don’ think Viktor Orbán has to represent both interests. He only has to represent one interest - the interest of Hungary. And Hungary’s interests coincide with the interests of the EU and NATO," Ilyas told Euronews.
However, Hungarian opposition parties are calling on Orbán to cancel his trip to Russia. They say it betrays the interests of both Hungary and Europe.