Canada's Gabriel Resources said Thursday Romania would get $30 billion in economic benefits if it approves a gold mine project at Rosia Montana that has drawn opposition from environmentalists.

"In total we have over $30 billion of economic benefits that come out of this project and remain in Romania, this equates to somewhere between 70 and 90 percent of the total benefits," Gabriel Resources CEO Jonathan Henry told AFP.

The figure is seven times higher than the amount initially promised by Gabriel Resources, but Henry stressed it was contingent on gold prices going up.

The Canadian firm which owns 80 percent of Rosia Montana Gold Corporation, with the Romanian state holding the balance, plans to extract some 300 tonnes of gold and 1,600 tonnes of silver over 16 years near the village of Rosia Montana, thought to lie on Europe's largest gold deposits.

Investment is expected to total at $1.7 billion.

Gabriel Resources is still waiting for a key environmental permit and a recent court ruling against zoning plans submitted by the firm may further delay the process, outgoing environment minister Attila Korodi said Thursday.

The fall of the center-right government last week and the appointment as prime minister of Victor Ponta, a leftist who has in the past been critical of the Canadians' plans, has sent Gabriel Resources share price plumetting.

"Our shareholders see far more risks in investment in Romania now than they did previously and that reflects in the share price," Henry said.

"We need to make sure the new government understands fully what this project means to Romania and how we are building it," he added.

Opponents, including environmentalists, archaeologists, historians and international organisations, claim the open-cast mine, which will use 12,000 tonnes of cyanide a year in the leaching process, threatens the environment and Roman-era mining galleries.

They insist it will lead to partially blowing up four mountains surrounding the village and damage part of the galleries, unique in Europe.

But Henry said the project will meet the highest Romanian and European standards.