(Bloomberg) -- A Colombian businessman close to Venezuelan President Nicolas Maduro is appealing a U.S. court decision to disregard his diplomatic immunity in a last-ditch effort to block his extradition to American soil over corruption charges.

As a Venezuelan envoy to Iran, Alex Saab should not have been arrested in the archipelago of Cape Verde off the West African coast, where his private plane stopped to refuel while flying from Venezuela to Iran last year, his legal team said in a statement Tuesday. Saab’s lawyers are challenging a ruling by a Miami district judge that refused to consider his immunity until he appears in the country.

Saab “is entitled to immunity from arrest, detention, and extradition to the United States,” they said in the statement.

The appeal comes after the Cape Verdian government disregarded an order by a West African court for Saab to be released from detention in the island nation. The U.S., which recently announced the construction of a new embassy as part of a $400 million investment in Cape Verde, has called for his extradition.

American authorities, which believe Saab holds information on how Maduro and his inner circle allegedly looted hundreds of millions of dollars from state coffers, have sought to crack down on officials accused of corruption in Venezuela.

Saab has already been indicted by a U.S. federal court in Florida on federal money-laundering charges related to bribing Venezuelan officials. He has denied the charges through his lawyers.

Prior to his arrest in Cape Verde, Saab had also been tapped to orchestrate deals that would exchange Venezuelan gold for Iranian gasoline.

©2021 Bloomberg L.P.