Greece's environment minister Wednesday announced a block to expansion work at a Canadian goldmine over alleged contract violations.

Energy Minister Panos Skourletis said he had ordered a "temporary" block on an expansion dig undertaken by Hellas Gold -- a subsidiary of Canadian firm Eldorado Gold -- on the mountain of Skouries, in the northern Halkidiki peninsula.

"The company has violated the terms of its technical studies. This means a temporary halt in work," Skourletis said, without elaborating.

The company could not immediately be reached for comment.

The investment by Hellas Gold, which already operates other mines in the area, has deeply divided the inhabitants, many of whom welcome the jobs created by the project.

Anti-mine protesters claim the project will cause irreversible harm to the environment, draining and contaminating local water reserves and filling the air with hazardous chemicals including lead, cadmium, arsenic and mercury.

A series of protests against the project included a violent one in 2013, when hooded militants threw Molotov cocktails at the mine worksite, wounding a guard and damaging equipment.

While in opposition, the now ruling Syriza party publicly opposed the investment.

"The government welcomes investment, but companies must respect the terms to which they are bound," Skourletis said Wednesday.

The move came as the leftist Greek government seeks to rebuild investor confidence by authorising privatisations it had previously opposed.