LISBON, Portugal (AP) — Portuguese police have arrested the chief of staff of Prime Minister António Costa while making multiple raids of public buildings and other properties as part of a widespread corruption probe, the prosecutor’s office said Tuesday.

An investigative judge issued arrest warrants for Vítor Escária, Costa’s chief of staff, the mayor of Sines, and three other people because they represented a flight risk and to protect evidence, the prosecutor’s office said in a statement.

It said that the Minister of Infrastructure João Galamba and head of the country’s environmental agency were among those named as suspects.

The judge is investigating alleged malfeasance, corruption of elected officials, and influence peddling related to lithium mines concessions near Portugal’s northern border with Spain, and plans for a green hydrogen plant and data center in the southern coastal town of Sines.

The raids included the premises of the Ministry of the Environment, the Ministry of Infrastructure, the Sines town council, private homes and offices.

The prosecutor’s office said that the probe has determined that the “suspects invoked the name of the prime minister” when carrying out their allegedly illicit activities.

Costa, a Socialist, has been in power since 2015.

Portugal’s lithium mines and green hydrogen projects are part of the continent’s green initiative being pushed by the European Union.