Paris: French President Emmanuel Macron on Friday condemned the annexation of Ukrainian territories by Russia and said that the act is a serious violation of international law and Ukrainian sovereignty.

He added that the move is opposed by France and it continues to stand with Ukraine in its battle against Russia to regain its territories.

In a tweet, Macron wrote, "Russia's "illegal" move to annex four Ukrainian regions, describing the act as a "serious violation of international law and Ukrainian sovereignty."

"France opposes this and will continue to stand alongside Ukraine to confront Russian aggression and allow Ukraine to recover its full sovereignty over all of its territory," he tweeted on Twitter.

The annexation has been widely criticized by the west.

Notably, the United States on Friday announced that it will impose a "swift and severe cost" on Russia after President Vladimir Putin announced the annexation of four regions of Ukraine, which America quoted as a 'sham referendum.'

Calling the annexation "illegal", Biden said that the US will always honour Ukraine's internationally recognized borders and will continue to support the country's effort to regain control of its territory by strengthening its hand militarily and diplomatically.

He further said that the USD 1.1 billion in additional security assistance that the United States announced this week also helped Ukraine.

"We will continue to provide Ukraine with the equipment it needs to defend itself, undeterred by Russia's brazen effort to redraw the borders of its neighbour," the statement reads.

US President also said he will sign legislation from Congress that will provide an additional USD 12 billion to support Ukraine.

Putin signed the documents to formally announced the annexation of four regions - Donetsk, Luhansk, Kherson and Zaporizhzhia.

Meanwhile, US Secretary of State Antony Blinken said that the "United States unequivocally rejects Russia's fraudulent attempt to change Ukraine's internationally recognized borders."

"We will continue the United States' powerful, coordinated efforts to hold Russia to account, cut Russia's military off from global commerce and severely limit its ability to sustain its aggression and project power," he added.

Moreover, the European Union leaders also unequivocally condemned the illegal annexation by Russia of Ukraine's Donetsk, Luhansk, Zaporizhzhia and Kherson regions and accused the Kremlin of putting global security at risk.