Portugal’s socialist prime minister, António Costa, has resigned hours after prosecutors examining alleged corruption involving lithium and “green” hydrogen deals announced that he was under investigation and police searched dozens of addresses, including his official residence and the environment and infrastructure ministries. Speaking on Tuesday afternoon after two emergency meetings with Portugal’s president, Marcelo Rebelo de Sousa, Costa said he had submitted his resignation, adding he had a “clear conscience” and “complete trust in justice” and how it worked. “The duties of prime minister are not compatible with any suspicion of my integrity,” he told a press conference. “In these circumstances, I have presented my resignation to the president of the republic.” Costa, who won a third consecutive term as prime minister after his party secured a surprise absolute majority in a snap general election in January 2022, said he had stepped down despite having been “completely willing to dedicate myself with all my energy to fulfilling the mandate until the end of this legislature”. He also said he would not be running in any forthcoming elections. His announcement came after the Portuguese press reported that at least five people had been detained, including Costa’s chief of staff, Vítor Escária, and Costa’s friend, the business consultant Diogo Lacerda Machado. The public prosecutor’s office then revealed that Costa himself was being investigated, adding the prime minister’s “name and authority” had been cited by suspects questioned during the investigation. Rebelo de Sousa confirmed that he had accepted Costa’s resignation and would be meeting party leaders on Wednesday. The president will then have to decide whether to dissolve parliament and call an election, or whether to allow Costa’s socialists, who have a majority in parliament, to form a new government. In January this year, prosecutors said they were looking into allegations of corruption relating to lithium and hydrogen projects but did not name any suspects. The investigation into the alleged “misuse of funds, active and passive corruption by political figures, and influence peddling” involves lithium mining concessions in the north of the country. It is also investigating a hydrogen production project and datacentre to be built by the company Start Campus in Sines, a town about 60 miles south of Lisbon. In a statement released on Tuesday, prosecutors said 42 premises had been searched by police and staff from its Criminal Investigation and Action Department. It confirmed that the addresses searched “in order to identify and seize documents and others relevant evidence” had included “spaces used by the head of the prime minister’s office”, the two ministries and the Sines town council. Citing flight risk and the possibility that illegal activity could continue, prosecutors said arrest warrants had been issued for Costa’s chief of staff, the mayor of Sines, and two executives at Start Campus. Prosecutors also said that Portugal’s infrastructure minister, João Galamba, had been indicted as part of the investigation, as had the president of the executive board of the Portuguese Agency for the Protection of the Environment (APA). In May, the APA approved a mining project for lithium, an essential metal for the manufacturing of electric batteries. A second project was given the green light at the start of September.