A Belgian judge charged four people on Sunday over allegedly receiving money and gifts from a Gulf state to influence decisions in the European Parliament, accusations that have caused consternation in Brussels.

Prosecutors searched 16 houses and seized 600,000 euros ($631,800) in Brussels on Friday as part of an investigation into money laundering and corruption.

Six people were initially detained. Four have been charged and two released, prosecutors said in a statement. They did not name any of those involved.