* Eldorado halted from developing mine in northern Greece
* Case tests Tsipras govt's approach to foreign investment
By Angeliki Koutantou
ATHENS, Oct 2 (Reuters) - A Canadian company appealed to Greece's top court on Friday to overturn a ban on its plans to develop a gold mine in a forested area of northern Greece, in a case widely seen as a test of the leftist government's approach to foreign investment.
Vancouver-based Eldorado's venture to extract gold and other ores on the verdant Halkidiki peninsula is seen as one of the top investments in a country racked by a debt crisis since the end of 2009. The company has put in more than $600 million since 2012 and plans to invest another $1 billion in its quest for gold, copper and zinc at two other sites.
But a day before resigning to call a general election, Prime Minister Alexis Tsipras' government revoked Eldorado's permit for the Halkidiki mine in mid-August, citing environmental grounds, in a move that showed Greece remains a risky bet for investors.
Eldorado then suspended all its activities at the mine and made most of its 1,300 workers temporarily redundant.
Some 500 of its workers demonstrated on Friday in support of the company's appeal outside the Council of State, Greece's highest administrative court, some carrying a banner that proclaimed: "No future without the ores".
Their trade union has joined the company's lawsuit against Greece's energy ministry, which had tried to block the investment since February. On Aug. 19, Energy Minister Panos Skourletis, a hardline leftist, accused Eldorado's Greek unit, Hellas Gold, of violating environmental safety guidelines.
After hearing oral arguments for about two hours, the court gave both sides until Oct. 7 to make full written submissions, Eldorado's lawyer Eleni Trova told reporters.
The court will hold several sessions before it issues a ruling.
"We're awaiting the court's ruling which we believe will vindicate us," said Yiorgos Hatzis, head of the workers' union, after the hearing. "People in Halkidiki are tired of being unemployed because of unfair decisions."
The high-profile case came to court in a week when Tsipras, who won re-election on Sept. 20, appealed to foreign investors on a visit to the United States to put their money in Greece's future.
"The message to investors is that they are welcome in Greece," he said at a Clinton Global Initiative event on Sunday. "The message is that now we have stability and a government with a clear mandate from the Greek people to make all the necessary changes. So they have nothing to lose."
That's not the way it looks to Eldorado or to investment bankers advising foreign companies in Greece.
"The issue has a very bad resonance abroad and doesn't help in attracting investors at all," said one investment banking director of an Athens-based bank, speaking on condition of anonymity.
Investor interest in Greece had edged up after the country signed up to an 86 billion euro ($96 billion) third bailout with euro zone governments last month, he said, but there was still a long way to go to restore business confidence.
Athens University economist George Pagoulatos said the ban looked like a political gambit to rally voters for Tsipras' leftist Syriza party in northern Greece before the election, and the government would probably be relieved to be overruled by the supreme court now.
The court is also expected to decide on a request by the company and its workers for an injunction that could open the way for a temporary resumption of works at the mine before the final verdict. ($1 = 0.8961 euros) (Writing by Paul Taylor; Editing by Mark Trevelyan)