Russian Deputy Foreign Minister Alexander Grushko said Thursday that Moscow would respond if the European Union (EU) decides to confiscate the country's frozen assets, TASS news agency reported, citing the official.

Grushko said that Russia would take "all the necessary measures to protect its legitimate interests" if the EU decides to go through with the decision.

He called the actions of the EU "completely illegal," adding that many countries are uncertain whether such a move would be in line with international norms.

EU representatives met in Brussels on Wednesday, where they approved "the establishment of an ad hoc working party on the use of frozen and immobilized Russian assets to support Ukraine's reconstruction," the Swedish EU Council Presidency said in a Twitter post.

The Swiss Federal Council issued a statement on the same day, saying that "a working group led by the Federal Office of Justice concluded that the confiscation of private Russian assets would undermine the Federal Constitution and the prevailing legal order."

In the run-up to a two-day EU summit, the leaders of Poland, Latvia, Lithuania and Estonia said that "in order to be credible on this matter vis-a-vis Ukraine," the bloc had to go beyond reiterating previous commitments and "accelerate our work in the council right now."

The four countries want Western governments to use Russia's €300 billion ($320 billion) of frozen central bank reserves to help Ukraine's internally displaced people and start rebuilding the country.

"Those frozen assets must be used as soon as possible. We cannot wait until the crisis is over and a peace agreement is signed," the four wrote in a joint letter to EU leaders Ursula von der Leyen and Charles Michel, and Sweden's prime minister, Ulf Kristersson. 

Sweden currently holds the rotating presidency and is responsible for drawing up agendas for the EU council of ministers.

(Cover: A woman walks past a currency exchange office in Moscow, Russia, February 16, 2023. /CFP)

(With input from agencies)