Thousands of Greek protesters on Saturday rallied against a Canadian gold mining project under way in the northeastern region of Halkidiki, which locals say will cause irreversible damage to the environment.
About 2,000 people took part in the march in Athens and another 1,500 in Greece's second-largest city Thessaloniki, according to AFP journalists.
Carrying banners against the project run by Hellenic Gold, a subsidiary of Canadian firm Eldorado Gold, the demonstrators chanted: "We want forests, land and water, not a grave made out of gold."
"Fields full of cyanide and arsenic, that is what remains from gold" was another slogan.
They also called for the release of two people who were arrested earlier this week in connection with a sabotage attack carried out on the mining worksite two months ago.
Citizens' groups have been trying to halt the project since 2011, when the Greek government gave Hellenic Gold permission to dig in the region.
While the investment is expected to create hundreds of jobs in the recession-hit country -- where the unemployment rate has topped 27 percent -- opponents say it will drain and contaminate local water reserves and fill the air with hazardous chemicals including lead, cadmium, arsenic and mercury.
Frequent marches have taken place in recent months, with protesters enjoying the backing of main opposition radical leftist party Syriza, the second-largest in parliament.
In the February attack, dozens of hooded activists firebombed Hellenic Gold's worksite, injuring a guard and damaging equipment.
Earlier this week, angry locals trashed the police station of the nearby Ierissos village over claims that officers had used excessive force in the pre-dawn arrest of the pair suspected to be linked to the sabotage attack.
Public Order Minister Nikos Dendias accused the local community of Ierissos of wanting "to impose its own law and operate like a Gaulish village," in a reference to the Asterix comic books.
Despite the opposition, the Canadian firm announced earlier this month that it intends to remain in Greece and create thousands of jobs over the next two years.
Halkidiki, a picturesque and forested peninsula, is a popular destination for tourists, especially from Russia and the neighbouring Balkan states.