Russia has vowed to inflict further energy pain on any country supporting the decision by the US Congress to approve a further a $US45 billion ($A67 billion) aid package for Ukraine.

The aid measure passed by the Democratic-controlled house, part of a $US1.66 ($A2.48) trillion government funding bill that won Senate approval a day earlier, will now go to US President Joe Biden for signing into law.

In a tweet thanking Congress and leaders of both parties, Zelenskiy said it was “crucial” that Americans remain “side-by-side” with Ukrainians “in this struggle”.

He also warned his countrymen that Russia may well launch further attacks over Christmas and urged them to heed air raid alarms.

The new military and economic assistance would come atop some $US50 billion ($A75 billion) in aid to Ukraine this year as well as Western sanctions on Russia that now include a cap on Russian oil prices.

Russia responded to the cap on Friday by threatening to cut oil output by five to seven per cent early next year by halting sales to countries that support the measure.

Tweet from @ZelenskyyUa

Republicans – some of whom have voiced increasing scepticism about sending so much aid to Ukraine – are set to take control of the US House of Representatives from Democrats on January 3.

Zelenskiy has long sought Patriot missiles to help counter relentless Russian air strikes, which have razed cities, towns and villages during 10 months of brutal conflict and knocked out power and water across the country over the past three months.

US officials say, however, that the single Patriot battery that President Joe Biden told Zelenskiy would be supplied to Ukraine would not change the course of the war.

Washington and its allies have been unwilling to supply Kyiv with modern battle tanks and long-range missiles called ATACMS that could reach far behind frontlines and into Russia itself.

It is unclear whether US Congressional support to Ukraine would endure after Republicans take charge of the House.

Even as it fights for its survival, Ukraine is pursuing a fight against domestic corruption to help reassure international donors that their money will be spent well.

Russian President Vladimir Putin said Moscow would find a way to counter the Patriots while also seeking to end the fighting.

‘War’ or ‘special military operation’

“Our goal is not to spin the flywheel of military conflict, but, on the contrary, to end this war,” he said.

In response, White House spokesman John Kirby said Russia’s actions showed Putin was clearly set on escalating its invasion.

By using the word war, Putin departed from the usual Kremlin practice of referring to its invasion as a “special military operation”.

A politician in St Petersburg asked prosecutors to investigate Putin over his use of the word, accusing the Kremlin chief of breaking his own laws on spreading “disinformation”.

Nikita Yuferev, an opposition councillor in the city where Putin was born, said he knew his legal challenge would go nowhere, but filed it to expose the “mendacity” of the system.

“War, in Russian society, is a frightening word. Everyone is brought up by grandparents who lived through World War Two, everyone remembers the saying ‘Anything but war’,” he said.

The Kremlin said “significant progress” had been achieved towards its stated goal of “demilitarising” Ukraine.

Kyiv and its Western allies say Moscow is fighting an illegal war of conquest and suspect its repeated offers of negotiations on its own terms are a ploy to buy time after battlefield setbacks.

“We are coming back from Washington with …something that will really help,” Zelenskiy said on his Telegram channel. In later posts, he said he was back in Kyiv and working towards “victory”.

Ukraine has driven Russian forces from its capital Kyiv and second biggest city Kharkiv and Moscow is now focused on holding on to areas they occupy in southern and eastern Ukraine – around a fifth of the country.

-with AAP