"Let us reflect on the condition of the country and of our society in terms of solidarity and cohesion," said Venizelos, who served as finance minister for eight months before resigning to lead the Socialists.
Conservative party head Antonis Samaras said the tragedy highlighted the urgency of getting Greece out of the crisis.
"Unfortunately, this is not the first (suicide)," he said. "They have reached record levels."
Associated Press Television News' Efty Katsareas contributed.
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