WASHINGTON, May 28 (Reuters) - Ryan Salame, the former co-CEO of FTX's Bahamian subsidiary and a top lieutenant to the bankrupt cryptocurrency exchange's founder, Sam Bankman-Fried, was sentenced on Tuesday to 90 months in prison, U.S. federal prosecutors said on Tuesday.

Salame pleaded guilty in September to making tens of millions of dollars in unlawful campaign donations to boost causes supported by his boss.

Bankman-Fried himself was sentenced earlier this year to 25 years in prison for stealing $8 billion from FTX customers. A jury found him guilty in November on seven fraud and conspiracy counts stemming from FTX's 2022 collapse, which prosecutors have called one of the biggest financial frauds in U.S. history.

Prosecutors say Salame, Bankman-Fried and former FTX engineering chief Nishad Singh used FTX customer funds to donate to political candidates supporting crypto-friendly legislation.

In addition to the prison term, Salame, 30, was sentenced to three years of supervised release and ordered to pay more than $6 million in forfeiture and more than $5 million in restitution, prosecutors said in a statement on Tuesday.

"Salame's involvement in two serious federal crimes undermined public trust in American elections and the integrity of the financial system," said Damian Williams, U.S. Attorney for the Southern District of New York.

Salame, who could not immediately be reached for comment, gave more than $24 million to Republican candidates and causes in the 2022 election cycle, according to Federal Election Commision data, making him one of that year's top donors.

He had pleaded guilty to one count of conspiracy to make unlawful political contributions and one count of conspiracy to operate an unlicensed money transmitting business. (Reporting by Kanishka Singh in Washington; editing by Rami Ayyub)