The European Union must do more to counter Russia’s interference in Ukraine, where incursions threaten the bloc’s “very existence,” billionaire financier George Soros said.

“Europe needs to get its act together and prevent a financial collapse” in Ukraine, Soros said at a conference sponsored by the International Crisis Group in Brussels. “If Ukraine effectively collapses or is neutralized in this way,” then “the geopolitical consequences would be far-reaching,” Soros said.

Ukraine, where a truce has failed to halt daily skirmishes between government forces and pro-Russian factions, needs money to buy extra natural gas for the winter, to repair its coal mines, to “replenish” the central bank’s currency reserves and for debt exchange, Soros wrote in an article in the New York Review of Books that was posted on its website.

The International Monetary Fund should provide the country with “an immediate cash injection of at least $20 billion with a promise of more when needed,” Soros said in the article. The nation’s partners should provide additional financing “conditional on implementation of the IMF-supported program, at their own risk, in line with standard practice,” he said.

Ukraine, the EU and the U.S. say that Russian President Vladimir Putin has backed the separatist rebels with arms and troops. Russia denies the allegation.

EU’s ‘Tragedy’

Soros’s book, “The Tragedy of the European Union: Disintegration or Revival?” looks at the challenges facing Europe in a series of interviews between Soros and Der Spiegel correspondent Gregor Peter Schmitz. While the book contains observations on the structural flaws in the euro and the EU’s handling of the financial crisis, Soros reiterates his faith in the EU as a model of open society.

Russia’s maneuvers in Ukraine pose a threat to the 28-nation bloc’s existence, according to Soros.

“The Russian attack on Ukraine is indirectly an attack on the European Union and its principles of governance,” Soros said in the article. “All available resources ought to be put to work in the war effort even if that involves running up budget deficits.”

While the Sept. 5 cease-fire agreement remains in place, “Putin retains the choice to continue the cease-fire as long as he finds it advantageous or to resume a full-scale assault,” Soros said.

Pro-Russian rebels vowed to keep battling Ukrainian government forces and expand their territory by retaking control of cities including the port of Mariupol.