Russian President Vladimir Putin has lashed “scum and traitors” in a chilling speech amid increasing speculation his invasion of Ukraine is not going to plan.

Mr Putin used the speech to deliver a stark warning to Russian “traitors”, who he said the West wanted to use to destroy the country.

“Of course they (the West) will try to bet on the so-called fifth column, on traitors – on those who earn their money here, but live over there. Live, not in the geographical sense, but in the sense of their thoughts, their slavish thinking,” he told government ministers on Wednesday (local time), three weeks into Russia’s war with Ukraine.

“Any people, and especially the Russian people, will always be able to distinguish the true patriots from the scum and the traitors, and just to spit them out like a midge that accidentally flew into their mouths.”

The war has settled into a grinding pattern of sieges of cities, with Ukrainian officials reporting Russian attacks on schools, hospitals and cultural facilities. On Thursday (local time), the search for survivors who were sheltered in a drama theatre in the besieged town of Mariupol was to resume.

Rescuers in the southern port city dug survivors from the rubble after officials said the theatre was hit by an air strike on Wednesday as more than 1000 civilians – including many children and the elderly – sheltered there. The number of casualties is not yet known. Russia denies striking the theatre.

The United Nations human rights office in Geneva said it had recorded 2032 civilian casualties so far in Ukraine – 780 killed and 1252 injured. Some 3.2 million civilians have fled to neighbouring countries.

With sanctions increasing further against Russia, Mr Putin said the West was trying to divide his nation and provoke civil confrontation.

“There is one aim – the destruction of Russia,” he said.

“I am convinced that this natural and necessary self-cleansing of society will only strengthen our country, our solidarity, cohesion and readiness to meet any challenge.”

Mr Putin’s incendiary speech left some worried that the Russian leader, facing tougher resistance than he expected in Ukraine, would take a vengeful turn at home and crack down more forcefully than ever on any sign of dissent.

Russian opposition politician Mikhail Kasyanov, who was Mr Putin’s first prime minister in the early 2000s, condemned the remarks on Twitter.

“Putin is intensifying his actions to destroy Russia and is essentially announcing the start of mass repressions against those who don’t agree with the regime,” he said.

“This has happened in our history before, and not only ours.”

Moscow-based political analyst Andrei Kolesnikov said: “Putin, in an Orwellian way, has divided the citizens of Russia into clean and unclean.”

Russia pulls UN Security Council vote

The UN Security Council will no longer vote on Friday on a Russian-drafted call for aid access and civilian protection in Ukraine as Russia’s UN envoy accused Western countries of a campaign of “unprecedented pressure” against the measure.

Diplomats said the Russian move would have failed, with most of the 15-member council likely to abstain from a vote on the draft resolution because it did not address accountability or acknowledge Russia’s invasion of its neighbour.

Nor did it push for an end to the fighting or a withdrawal of Russian troops.

“Many colleagues from many delegations tell us about unprecedented pressure by Western partners, that their arms are being twisted, including blackmail and threats,” Russia’s UN Ambassador Vassily Nebenzia said.

At a council meeting on Ukraine’s humanitarian situation, requested by Western council members, Mr Nebenzia said: “We do understand how difficult it is for those countries to withstand this kind of onslaught.”

US Ambassador to the United Nations Linda Thomas-Greenfield said: “The only people who do arm-twisting around here are the Russians and they have to if they want to get anybody to support them.”

Mr Nebenzia said Russia had instead requested the council meet on Friday – when the vote had been scheduled – to discuss “US bio-laboratories in Ukraine using the new documents we obtained in the course of the special military operation”.

At a security council meeting on the same issue last week, also requested by Russia, Ms Thomas Greenfield said there were no Ukrainian biological weapons laboratories supported by the US. The UN also said it had no evidence Ukraine had a biological weapons program.

-with AAP