Following the resignation of Antonio Costa as prime minister of Portugal on Tuesday, activists have taken to the streets to protest against lithium projects. The protestors want the government to suspend them due to alleged corruption in the handling of the “green” energy deals.

Costa resigned hours after his chief of staff was detained, along with five others. The detainees named two formal suspects close to the ex-prime minister in the investigation into lithium and hydrogen projects.

In September, Portugal’s environment agency, APA, gave approval to local company Lusorecursos to extract battery-grade lithium and for London-based Savannah Resources to develop four open-pit mines, with production set to commence by the end of 2027. Both the mines are in northern Portugal, near the border with Spain

Local residents and environmentalists oppose the lithium projects, saying the processes lacked transparency, and have repeatedly warned of the “dangerous promiscuity” between government and mining companies.

Savannah said in a statement that it was cooperating with the authorities that visited the locations but that the company and its staff members were not the target of the investigation.

Eight anti-mining groups said in a joint statement that the prime minister’s resignation and the detainments were proof their concerns over corruption were legitimate.

The United in Defence of Covas do Barroso (UDCB) movement, which is protesting against Savannah Resources’ project in the Barroso region, said the environmental approval first granted by the APA should be reviewed.

The UDCB said: “Suspension of any licensing, prospecting or exploration licences is imperative until criminal responsibilities can be properly ascertained.”

Portugal has been seen as a key nation in Europe’s return to domestic mining, as it has more than 60,000 tonnes of known lithium reserves. Portugal is currently Europe’s biggest lithium producer.