In federal court in Miami on Monday, a close supporter of Venezuelan President Nicolas Maduro is likely to enter a not guilty plea to money laundering allegations, further straining already tense relations between Washington and Caracas.

Prosecutors allege that Alex Saab, a Colombian businessman and top dealmaker for Maduro’s socialist administration, smuggled $350 million out of Venezuela via the United States as part of a bribery conspiracy involving the country’s state-controlled exchange rate.

Last week, one of Saab’s lawyers, Henry Bell, told Reuters that his client would enter a not guilty plea at his arraignment on Monday.

The opposition in Venezuela has said it expects Saab will tell US law enforcement agencies what he knows about any illegal conduct by top Venezuelan officials, as well as the government’s methods to avoid US sanctions aimed at deposing Maduro.

Maduro has been branded a corrupt tyrant by the United States, who blames him for the OPEC country’s economic catastrophe.

Saab was extradited from Cape Verde in October when his plane was stopped for refueling in 2020.

Following the arrest, Venezuela’s government said Saab had been granted Venezuelan citizenship and named a diplomat to negotiate shipments of fuel and humanitarian aid from Iran.

In response to the extradition, Maduro’s government last month suspended nascent negotiations with the opposition.

Maduro’s allies have characterized Washington’s pursuit of Saab as part of an “economic war” on Venezuela being waged by the U.S. government.

The U.S.-backed opposition, which has called on Maduro to resume the talks, has said Saab became wealthy as a result of the deals he made with the government and did nothing to relieve the suffering of Venezuela’s citizens.

In a Jan. 21 court filing, Saab’s attorneys called the corruption charges a “cryptically alleged scheme” and said he denied the allegations.

“Mr. Saab denies this scheme and all allegations of the indictment concerning it or any conspiracy, bribery, or money laundering of any kind,” his attorneys wrote.