Spanish police Monday announced the seizure of 25 million euros ($35 million) in cash and the arrest of 20 people in an operation against \"the biggest money-laundering and drug-trafficking network in Europe.\" A total of 16 people were detained in Spain and four in the United States, said the police, who worked in cooperation with the FBI and judicial authorities in Miami. It was \"the biggest quantity of cash seized at one time,\" they said in a statement. It said authorities seized 21 properties in Spain and four in the United States worth a total of 75 million euros, as well as 60 cars. \"One of the money-laundering methods was to buy and sell luxury cars,\" the statement said. Spain\'s proximity to north Africa, a key source of hashish, and its close ties with its former colonies in Latin America, a major cocaine producing region, have made it a major gateway into Europe for drug traffickers.