The EU on Monday denounced a decision by Serbia to hold regular foreign policy consultations with Russia, saying the move raised “serious questions” at a time when Brussels has told membership candidates not to continue business as usual with Moscow.

Russia’s Foreign Minister Sergei Lavrov and his Serbian counterpart Nikola Selakovic signed a document on Friday dubbed a “plan on consultations”.

Selakovic said that the plan envisages consultations on bilateral and multilateral activities, though there was nothing on security policies in it. Serbian opposition parties criticised the document.

Serbia, which was bombed by NATO two decades ago but now seeks to join the European Union, has long struggled to balance historically close ties with Russia against aspirations for economic and political integration with the West.

Speaking to reporters in Brussels on Monday, Peter Stano, a spokesperson for the EU’s executive commission, noted that the new Russian-Serbian consultation document had been signed just days after Moscow announced a mobilisation for the Ukraine war and began to stage votes to annex territory it has captured.

The Serbia-Russia agreement was “a very clear sign about their intention to strengthen their ties”, Stano said. “And this is raising serious questions”.

The EU had been very clear with countries seeking to join that relations with Russia under current circumstances could not be business as usual, he said. Serbia had declared EU accession a strategic priority, which implied “alignment with European policies, including on foreign policy issues,” he added.

“We are taking this very seriously and we are following this up,” he said.

Serbian officials did not immediately respond to a request for comment on Stano’s remarks.

Although Serbia has condemned Russia’s invasion of Ukraine at the United Nations, it has refused to join sanctions against Moscow.