Portugal’s Prime Minister Antonio Costa announced his resignation on Tuesday following revelations he was under investigation for alleged misconduct in the awarding of public energy contracts.

“The duties of the prime minister are not compatible with any suspicion of my integrity,” Costa told reporters after meeting with President Marcelo Rebelo de Sousa earlier that day. “In these circumstances, I have presented my resignation.”

Portuguese media had reported earlier that police searched several government offices, including Costa’s, as part of an ongoing corruption probe.

Prosecutors later confirmed they indicted Infrastructure Minister Joao Galamba and issued an arrest warrant for Costa’s chief of staff over alleged “misuse of funds, active and passive corruption by political figures, and influence peddling.”

A separate line of inquiry involves Costa himself, who prosecutors say personally intervened to accelerate the contracts in question.

The widening investigation centers on lithium mining concessions in northern Portugal, a hydrogen production project, and a data center commissioned by local tech firm Start Campus.

Citing flight risk and ongoing illegal activity, prosecutors also issued arrest warrants for Sines’ mayor and two Start Campus executives linked to the deals.

Additionally, the president of Portugal’s Environmental Protection Agency was indicted after greenlighting a contested lithium mining project in May, followed by a second approval in September. Environmentalists argue that mining clashes with sustainability.

Portugal harbors Europe’s largest lithium reserves but currently only supplies the material to glass and ceramic industries. Lithium is a vital component of electric vehicle batteries.

Costa had led Portugal’s Socialist Party since 2015 after a series of scandals plagued the previous administration. But his popularity waned recently over controversies around the national airline TAP.