The stock closed trading on 7 July with its share price at 2.1 pence (US$0.02), which is down 7% day on day, and 40% lower than where it started the week. It's the weakest closing value since 2.02p on 8 October, 2020.

Archer, who served as CEO for almost nine years, will be succeeded on an interim basis by Dale Ferguson, the company's technical director, during the search for a full-time replacement.

"I am stepping down with a very strong team in place to execute on Savannah's next phase and I wish everyone great success and, as a committed long-term shareholder, will be closely following the future of Savannah," Archer said.

Meanwhile, Portugal's environmental regulator, Agencia Portuguesa do Ambiente has requested—to which Savannah agreed—that the Environmental Impact Assessment process include "Article 16", which, while drawing out the process, should still see the project able to supply Europe's first generation of lithium conversion plants as they come online in the mid-2020s, Savannah said.

The optional step in the EIA evaluation process is designed to allow adjustments to the project in accordance with the feedback of the stakeholders involved in the process.

"While this additional stage in the environmental licensing of the project adds to the overall development schedule, it does have a clearly defined timeline in law," Ferguson said.

Savannah will endeavor to submit any revised plans to APA "as soon as practicable", but under the legislation, a Declaration of Environmental Impact decision would be reached no later than March next year, he said.

"Assuming a positive DIA decision is received at that time, or before, we believe the project's development would still be on track," he said.

Previously, Savannah had guided that it was hopeful that the EIA would be approved by the regulator within this year.

WH Ireland Capital Markets said in a research note that the move by the APA should be viewed as a positive.

It "provides a timeline for issuance of the DIA decision and a mechanism through which any issues that need resolving can be addressed," it said.

"It remains our opinion that Savannah is poised and ready to rerate once we have clarity on the EIA. The Barroso project is a simple, low-risk operation in our view, utilizing standard recovery methods of lithium into an intermediate spodumene concentrate in an economic area crying out for domestic supply," it said.

Savannah intends for its project it generate enough lithium for about 500,000 electric vehicle battery packs per year.