LISBON, Portugal (AP) — Portuguese Prime Minister António Costa said Tuesday he is resigning after being involved in a widespread corruption probe.

Costa said in a nationally televised address that “in these circumstances, obviously, I have presented my resignation to the president of the republic.”

Costa’s shocking announcement came hours after Portuguese police arrested his chief of staff while raiding several public buildings and other properties as part of a widespread corruption probe.

The Supreme Court, the state prosecutor’s office said, was also examining the suspects’ “use of the prime minister’s name and his involvement to unlock” the practices being probed.

The 62-year-old Costa, Portugal’s Socialist leader since 2015, defended his innocence.

“I totally trust the justice system,” he said.

Portuguese president Marcelo Rebelo de Sousa is expected to accept his resignation.

An investigative judge issued arrest warrants for Vítor Escária, Costa’s chief of staff, the mayor of the town 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 the 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 mine concessions near Portugal’s northern border with Spain, and plans for a green hydrogen plant and data centre in Sines, on the south coast.

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.

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