The probe involving Costa and others covers alleged"misuse of funds, active and passive corruption by political figures, and influence peddling," according to a statement from public prosecutors.
"In these circumstances, I have presented my resignation to the president of the Republic," he added. "The President of the Republic will address the nation immediately after the meeting of the Council of State," the statement added. The investigation covers lithium mining concessions in the north of the country, as well as a hydrogen production project and data centre to be built by the company Start Campus in Sines, a town about 100 kilometres south of Lisbon.
A second project was given the green light at the start of September. The projects are opposed by environmental groups and part of the local population. His popularity has recently declined after a series of scandals, including one linked to the national airline TAP.