Portugal's Prime Minister Antonio Costa resigned on Tuesday amid an investigation into alleged irregularities committed by his majority Socialist administration in handling lithium mining and hydrogen projects in the country.
Costa announced the decision in a televised statement after meeting President Marcelo Rebelo de Sousa. He said he conscience was clear, but he would not stand as candidate for premiership again.
Prosecutors earlier on Tuesday named Infrastructure Minister Joao Galamba as a formal suspect and detained Costa's chief of staff. The opposition has demanded that the government step down with immediate effect.
Costa he was "fully available to cooperate" with the justice system after prosecutors said he was also the target of an investigation.
"The dignity of the functions of prime minister is not compatible with any suspicion about his integrity, his good conduct and even less with the suspicion of the practice of any criminal act," Costa told reporters.