Russian president Vladimir Putin has denied claims about a lavish palace allegedly built for his use on the Black Sea, as the Kremlin scrambles to respond to a wave of popular anger fuelled by jailed opposition leader Alexei Navalny.

Two days after Mr Navalny used the video to drive turnout at the largest anti-Putin protests in years last weekend, Mr Putin made the remarks in a stage-managed question-and-answer session on Monday with students.

They came as Josep Borrell, EU foreign policy chief, vowed to call for Mr Navalny’s release during a trip to Russia he is planning despite opposition from some member states, said bloc diplomats. EU foreign ministers meeting in Brussels on Monday also held back from pushing immediately for more sanctions against Moscow over the Navalny case, further underscoring the bloc’s internal divisions over policy towards the Kremlin.

Mr Navalny, a 44-year-old anti-corruption activist, released a two-hour film a day after he was jailed last week that used construction plans and financial documents to allege that oligarchs had spent billions on the palace near Gelendzhik, complete with a casino, a wine cellar, what appeared to be a strip club, and an “aqua disco”.

The video has racked up 86m views on YouTube since its release and was a major trigger for the protests last Saturday, as tens of thousands of Russians across the country called for Mr Navalny’s release. Leonid Volkov, who runs Mr Navalny’s regional network, said they would hold similar protests on Sunday.

Mr Putin said he “did not have time” to watch the video, but claimed that “nothing listed there has ever belonged to me or my close relatives”. He did not address most of Mr Navalny’s key claims, which included accusations that the palace is held through a complex beneficial ownership structure managed by his close associates and guarded by the presidential security detail.

“This is just a convenient moment to cobble together all these materials to brainwash our citizens and put it online,” Mr Putin said. “I’ve never been interested in business . . . I’ve never done it, ever.”

That Mr Putin — who refuses to speak Mr Navalny’s name in public and normally avoids discussing him at all — would address the film at all is highly unusual, indicating the Kremlin’s concern over the protests.

“The very fact that Putin commented on Navalny’s film is indirect acknowledgment that popular anger is justified,” Tatiana Stanovaya, founder of political consulting firm R Politik, wrote on messaging app Telegram. “But then the question arises: should the people take Putin at his word? OK, it’s not yours. But without an answer to the question about ‘who has the pleasure’ it looks ridiculous.”

In an attempt to discredit the protests, officials have accused Mr Navalny of using children as “human shields”, though an informal survey of the Moscow rally found that only 10 per cent of people there were under 18.

Mr Putin said: “You can’t push underage people to the forefront. That’s what terrorists do when they shove women and children in front of them.”

Investigators have filed several criminal charges over the protests after police detained a record 3,711 people, including 195 who were under 18, according to independent monitor OVD-Info.

State TV devoted air time to denouncing Mr Navalny on Sunday evening. Dmitry Kiselyov, the head of Russia’s main state news agency, said Mr Navalny and his allies were “political paedophiles” who tricked young people into “provoking violence” at the protests.

In a segment titled “A politician worthy of a toilet brush” — in reference to an Italian €700 Italian toilet scrubber that Mr Navalny said was bought for the palace — Mr Kiselyov accused the activist of smearing Mr Putin with forgeries provided by western secret services.

“First of all, Putin doesn’t need any luxury in his life. It’s not cool for him. He doesn’t have the time to play the slot machines in a casino in his house and smoke shisha,” Mr Kiselyov said, referring to other attractions Mr Navalny claimed were in the palace.

Additional reporting by Michael Peel in Brussels