CARACAS (Reuters) - Cape Verde has committed "constitutional suicide" by allowing the extradition of businessman and envoy Alex Saab to the United States on charges of laundering money for the government of Venezuelan President Nicolas Maduro, Saab's lawyers said on Thursday.

       Saab was on his way to Iran last year to negotiate shipments of fuel and humanitarian food supplies to Venezuela amid U.S. sanctions on the South America country when he was detained at a Cape Verde refueling stop.

       The West African nation's highest court on Tuesday upheld a lower court ruling that Saab, a Colombian national, should be extradited to the United States.

       "This sentence ... symbolizes the death of the rule of law so dear to Cape Verdeans, serving purely political interests according to an agenda dictated by Washington," Saab's legal team said in a statement sent to Reuters.

       "It is constitutional suicide!"

       Cape Verde Justice Minister Joana Rosa said the government does not comment on specific court rulings, but denied the assertions by Saab's lawyers about the judicial system.

       "The rule of law works in Cape Verde and the fact that the Alex Saab case has gone through all the judicial bodies shows that the institutions work," Rosa told Reuters.

       The State Department says Saab was helping Maduro organize trade deals that undermined Washington's sanctions program, which was created to force Maduro from power.

       U.S. prosecutors accuse Saab of bribing Venezuelan officials to take advantage of the state-controlled exchange rate and of transferring $350 million in illegally obtained funds to overseas accounts. Saab denies the charges.

       (Reporting by Deisy Buitrago in Caracas, additional reporting by Julio Rodrigues in Praia, writing by Brian Ellsworth; Editing by Aurora Ellis)