MOSCOW - Russian President Vladimir Putin said outstanding issues remain regarding the Ukraine peace plan after his meeting with US envoys at the Kremlin.

"There were such issues (with disagreements), and we discussed them, but it's difficult work," TASS quoted Putin as saying in an interview with India Today on Thursday.

Putin said the talks were necessary and concrete, adding that the US proposed 27 points, which were divided into four packages for discussion.

Every point of the peace plan was reviewed during their roughly five-hour meeting, according to Putin.

The Trump administration has taken on "a difficult task and a difficult mission" to reach a unanimous agreement on the Ukrainian conflict, Putin said.

Putin and US presidential special envoy Steve Witkoff held a meeting that ended after midnight on Wednesday. Russian Presidential Aide Yuri Ushakov described the meeting as "extremely useful, constructive and highly informative," saying that both sides reviewed documents previously conveyed by the United States and agreed not to disclose the essence of the talks. 

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Meanwhile, Russia will respond if the European Union seizes frozen Russian assets, Russian Foreign Ministry spokesperson Maria Zakharova said Thursday.

Moscow's response will be a "surprise" for the EU, said Zakharova, without providing further details.

She said that the behavior of European Commission President Ursula von der Leyen was "inappropriate."

Von der Leyen proposed a revised plan on Wednesday to use frozen Russian assets to support Ukraine, reducing the funding amount from up to $186 billion to around 105 billion dollars.

Belgium rejected the EU plan, saying the proposal fails to address the financial and legal risks it faces. Most of the frozen Russian assets are held in a Brussels-based securities depository Euroclear.