Adriatic was just waiting on an exploitation permit for Rupice, the underground part of Vares, which it said Monday it had duly received.

The permit was approved following a public hearing in Vares on July 7.

The permit means Adriatic can now proceed with construction, which it expects to begin in Q4.

Adriatic has taken Vares from discovery to fully permitted mine in just over four years, exceeding analyst expectations with the speed with which it has secured its permits.

Adriatic's CEO Paul Cronin said the final permit "marks the end of what has been a complex and multi-faceted permitting process".

"I am extremely proud of our team in Bosnia and Herzegovina for their diligence, coordination and cooperation with the many different stakeholders in the permitting process to make this happen," he said.

A definitive feasibility study is due in the coming weeks, which BMO Capital Markets analyst Alexander Pearce described as a key milestone.

"The company has continued to successfully deliver permitting milestones and is targeting first construction in Q4/21, which is in line with our current forecast (we assume first production in Q4/23)," he said.

"Note we estimate Adriatic requires circa US$200 million in total financing for the development, however, we look to the upcoming DFS for cost updates, which may be affected by COVID-19, cost inflation, etc.

"We currently estimate a 10% NPV of circa $740 million for the polymetallic project."

Adriatic shares fell slightly in London to 138p and last traded at A$2.48 in Australia.

BMO has an outperform rating and $3.25 price target.