A Beirut businessman accused of presiding over a multibillion-dollar commodities shipping empire and evading U.S. sanctions for financing terrorism pleaded not guilty to an 11-count criminal indictment unsealed in Washington on Thursday.

Kassim Tajideen, 62, a dual ­Lebanese-Belgian citizen, was charged March 7 with conspiracy, fraud and money laundering. He allegedly operated a network of companies from Africa to the Middle East that dealt in secret with U.S. businesses after sending tens of millions of dollars to the Shiite militant group and political party Hezbollah.

The prosecution of Tajideen, who was extradited to the United States after his arrest March 12 in Morocco, marked the latest move in a long-running U.S. effort to ramp up financial pressure against Iran-supported Hezbollah. The group has been a U.S.-designated terrorist organization since 1997 and is now fighting in support of Syrian President Bashar al-Assad’s regime in that country’s civil war.

Tajideen and his brothers, Ali and Husayn, lead a family business that has dominated poultry and rice markets, amassed real estate, and is reportedly active in construction and diamonds in Lebanon, the United Arab Emirates and western Africa, where Tajideen settled in Sierra Leone with his family in 1976. The three brothers were added to the U.S. government’s terrorism sanctions list in 2009 and 2010 for their prominent support of Hezbollah.

“The investigation of this case and the arrest and extradition of this defendant demonstrates our commitment to enforcing vitally important sanctions laws that are in place to protect our national security and foreign policy interests,” Channing D. Phillips, U.S. attorney for the District of Columbia, said in a statement announcing the arrest. “Because of the hard work of law enforcement here and abroad, Kassim Tajideen will now face charges in an American courtroom.”

Tajideen appeared relaxed in court Friday. He was detained at Casablanca’s airport while en route from Guinea’s capital, Conakry, to Beirut, on an arrest warrant issued two days earlier by Interpol’s Washington office, the Reuters news agency reported.

“He pleads not guilty,” defense attorney Matt Jones of the WilmerHale law firm told U.S. Magistrate Judge Robin M. Meriweather during a brief arraignment. Meriweather ordered Tajideen held pending a detention hearing March 29 and notification of the Belgian and Lebanese consulates.

On Friday, U.S. officials said Tajideen’s arrest capped “Project Cassandra,” a two-year Drug Enforcement Administration-led and U.S. Customs and Border ­Protection-aided investigation into Hezbollah’s global logistics and financing arm.

According to a 27-page indictment, Tajideen allegedly secretly restructured his multibillion-
dollar business after his May 2009 terrorist designation by the U.S. Treasury banned him from dealings with U.S. businesses.

U.S. authorities alleged that Tajideen and conspirators used new business names and misrepresented ownership to complete at least 47 fraudulent wire transfers totaling more than $27 million to unwitting U.S. vendors for illegal, unlicensed goods.

The Wall Street Journal in November reported that the Justice Department was investigating whether sales of wheat flour from Seaboard Corp., a Kansas-based food-processing giant known for its Butterball turkey brand, were being masked to firms linked to Tajideen.

Citing interviews with Tajideen and his civil lawyers, the Guardian newspaper in May reported that he had been working for several years with U.S. authorities to be removed from the terrorism blacklist. He argued that he was not a supporter of Hezbollah; that his actions were being conflated with those of his brother, Ali; and that he had severed ties with his brothers.

The U.S. indictment accused Tajideen of concealing his activities in representations to Treasury authorities in July 2010, December 2012 and April 2014, in which he claimed to present a “complete picture” of his financial holdings, submitted the results of forensic accounting investigations and committed to compliance with sanctions.

An earlier version of this article erroneously limited the 1997 U.S. terrorism designation for Hezbollah as applying to the group’s militant wing. The listing applied to the organization.