week - minister@
* Dozens of Eldorado Gold workers rally outside energy ministry
* Minister says to grant permits for Olympias project this week
* Says Skouries, metallurgical plant to be discussed in arbitration (Adds Greek energy minister, Hellas Gold quotes)
ATHENS, Sept 13 (Reuters) - Greece's Energy Minister assured protesting Eldorado Gold workers on Wednesday that it would grant outstanding permits this week to enable the Canadian miner to fully operate one of its Greek projects.
Eldorado Gold threatened on Monday to suspend investment at three Greek projects, demanding permits and clarifications on an upcoming arbitration process. Dozens of Eldorado Gold workers rallied outside the energy ministry earlier in protest at potential job losses.
Differences over the investment, one of the biggest in Greece in years, have dragged on for years, especially over compliance with environmental regulations, testing Greece's resolve to encourage foreign investments.
The company said on Monday that no additional investment would be made into Olympias and Skouries projects and the Stratoni mine from Sept. 22, only days after the leftist-led government urged investors to show confidence in Greece as it emerges from crisis.
"Licensing for Olympias...will be concluded in the coming days, today and tomorrow," Greek Energy Minister George Stathakis said in an effort to difuse tension. "Three permits will be issued as we announced in August, allowing Olympias to be fully operational."
Eldorado spent about 2 billion dollars to acquire the Greek asssets in 2012 and has invested over 1 billion dollars in developing them. It says it employs about 2,000 people in Greece, where unemployment stands at 21.2 percent, the euro zone's highest.
About 100 workers, in yellow vests, rallied outside the ministry early on Wednesday unfurling a banner reading "Occupation" in front of a police cordon. Some of them stormed into the building, according to one police official.
Police later fired some rounds of tear gas to disperse them.
Eldorado's Greek unit Hellas Gold welcomed Stathakis' comments:"We are pleased to hear the minister's comments although we've not received any permits yet. We look forward to receiving the outstanding permits for both Olympias and Skouries soon."
Eldorado's plans to develop its mine operations in the northern region of Halkidiki have provoked violent protests by locals who fear they will ruin a landscape of pristine beaches and lush forests.
It is sensitive for Prime Minister Alexis Tsipras' Syriza party, which strongly opposed the investment before coming to power in 2015. His government now says it wants the project as long as it is "environmentally and economically sound".
Stathakis said on Tuesday the ores that will be produced will contain arsenic, which will well exceed accepted levels, and therefore the government should make sure the company fully abides by environmental rules.
The government also wants a metallurgical plant as part of its contractual obligations. It says that Eldorado needs to provide further detail on its investment plans.
It has announced an arbitration process, which aims to resolve pending disagreements over the Skouries project and the metallurgical plant and is likely to start on Wednesday. It is expected to last at least three months.
"We hope it will solve all outstanding issues," he said. (Additional reporting by Lefteris Papadimas and Karolina Tagaris; Editing by Mark Trevelyan and Elaine Hardcastle)