WASHINGTON- President Joe Biden will ask Congress on Thursday for $33 billion to support Ukraine -- a dramatic escalation of U.S. funding for its war against Russia -- as well as new legal tools to tighten sanctions and siphon assets from Russian oligarchs, U.S. officials said.

The vast funding request includes over $20 billion for weapons, ammunition and other military assistance, as well as $8.5 billion in direct economic assistance to the government and $3 billion in humanitarian and food security aid.

Biden is also seeking the ability to seize more money from Russian oligarchs to pay for the war effort.

His proposal would have lawmakers hand his administration new capabilities, letting U.S. officials seize more oligarchs' assets, give the cash from those seizures to Ukraine and further criminalize sanctions dodging, the White House said.

The steps include letting the Justice Department use the strict U.S. racketeering law once deployed against the mafia, the Racketeer Influenced and Corrupt Organizations (RICO) Act, to build cases against people who evade sanctions.

Biden also wants to give prosecutors more time to build such cases by extending the statute of limitations on money laundering prosecutions to 10 years, instead of five. He would also make it a criminal act to hold money knowingly taken from corrupt dealings with Russia, according to a summary of the proposals.

The measures are part of U.S. efforts to isolate and punish Russia for its Feb. 24 invasion of Ukraine, as well as to help Kyiv recover from a war that has reduced cities to rubble and forced more than 5 million people to flee abroad.

The new request represents the full amount U.S. officials expect to need through September, the end of the fiscal year.

U.S. military aid to Ukraine alone has topped $3 billion since Russia launched what it calls a "special military operation" to demilitarize and remove fascists in Ukraine. Kyiv and its Western allies reject that as a false pretext.

The United States and its European allies have frozen $30 billion of assets held by wealthy individuals with ties to Russian President Vladimir Putin, including yachts, helicopters, real estate and art, the Biden administration has said.

Biden is expected to discuss the request for Congress from the White House at 10:45 a.m. (1445 GMT).

(Reporting by Trevor Hunnicutt; Editing by Robert Birsel and Alistair Bell)