Nigeria has released on humanitarian grounds an American citizen held for the past eight months on cryptocurrency money laundering accusations.

"I am pleased that American citizen and former U.S. law enforcement official Tigran Gambaryan has been released on humanitarian grounds by the Nigerian Government and is on his way back to the United States so that he can receive needed medical attention," U.S. national security adviser Jake Sullivan said in a statement.

"I am grateful to my Nigerian colleagues and partners for the productive discussions that have resulted in this step and look forward to working closely with them on the many areas of cooperation and collaboration critical to the bilateral partnership between our two countries."

Gambaryan was the chief compliance officer for Binance, the world's largest cryptocurrency exchange.

Nigeria accused Gambaryan and Binance of using Binance's platform to launder as much as $35 million, something Gambaryan and Binance have denied.

Earlier this week, a prosecuting lawyer with Nigeria's Economic and Financial Crimes Commission told Nigeria's Federal High Court that the government was ending the case against Gambaryan after "taking into consideration some critical international and diplomatic reasons."

Gambaryan's health declined in the months following his arrest. Reuters reports that his wife, Yuki, was concerned that his deteriorating condition could "leave permanent damage and affect his ability to walk."

Binance is facing additional charges, including suspicion of tax evasion and operating without a license.

Some information for this report was provided by The Associated Press and Reuters.