Portugal offers so-called "golden visas" to non-EU citizens who invest large amounts. Most are granted to Chinese who buy real estate. The 2-year-old program has brought investments totaling more than 1 billion euros (USD 1.2 billion).
Portugal's Attorney-General's office said in a statement that officials carried out more than 50 searches as part of the investigation today.
A separate police statement said 11 people were taken into custody on suspicion of corruption, money-laundering, influence peddling and embezzlement.