US Attorney General Loretta E. Lynch announces the filing of civil forfeiture complaints seeking the forfeiture and recovery of more than $1 billion in assets associated with an international conspiracy to launder funds misappropriated from a Malaysian sovereign wealth fund 1MDB in Washington July 20, 2016. [Photo/Agencies]

WASHINGTON - US prosecutors sued on Wednesday to seize more than $1 billion in assets they said were tied to money stolen from the Malaysian state development fund, which was overseen by the prime minister, and used to finance "The Wolf of Wall Street" film and to buy property and works of art.

Civil lawsuits filed in federal court did not name Malaysian premier Najib Razak, referring instead to "Malaysian Official 1." Some of the allegations against this official are the same as those in a Malaysian investigation over a $681 million transfer to his personal bank account.

The US Department of Justice said $681 million from a 2013 bond sale by sovereign wealth fund 1MDB was transferred to the account of "Malaysian Official 1." He is described in court papers as "a high-ranking official in the Malaysian government who also held a position of authority with 1MDB."

A source familiar with the investigation confirmed that "Malaysian Official 1" is Najib.

A spokesman for the prime minister said in a statement that 1MDB has been the subject of multiple inquiries in Malaysia.

"The Attorney General found that no crime was committed. 1MDB is still the subject of an investigation by the Royal Malaysia Police," the statement said.

The Malaysian government will cooperate fully with any lawful investigations, it said. Najib has consistently denied any wrongdoing.

The investigation is the largest set of cases brought by the US Department of Justice's Kleptocracy Asset Recovery Initiative, which seeks the forfeiture of the proceeds of foreign corruption. The previous largest case in February sought to seize $850 million.

1MDB, which Najib founded in 2009 shortly after he came to office, is being investigated for money laundering in at least six countries, including the United States, Singapore and Switzerland.

1MDB said in a statement that "it is not a party to the civil suit, does not have any assets in the United States of America, nor has it benefited from the various transactions described in the civil suit."

The fund said it has not been contacted by the Justice Department or any other foreign agency on the matter.