The man was arrested on Tuesday in Haidari by the Attica Security crimes of extortion squad and charged with blackmail.
Police said the accused had sent a hand-written letter to the casino's management on June 5, in which he demanded the return of 120,000 euro and threatened to set fire to himself within the casino grounds if they refused, so as to cause both damage and generate bad publicity. He claimed to have lost large sums while gambling.
Representatives of the casino contacted the man on the telephone and arranged that he should come to a meeting to receive 70,000 euro, at which time he was arrested. Police confiscated money which had been given to him in marked notes and a phone card that he had used in his telephone conversations with the casino.
He was led before the Athens first-instance court prosecutor.