The pair, who were arrested more than a month ago, stand accused of illegally entering Iranian waters.
A spokesman for the ministry told AFP the 52-year-old German would be represented by an Iranian lawyer from Bandar Abbas, in southern Iran, “who knows this kind of case well, having defended other foreigners”.
He said he did not know if the Frenchman would go on trial at the same time.
The German and the Frenchman were on holiday in the United Arab Emirates when they were reported missing on November 29 by the German’s wife, who was also holidaying with them.
The German foreign ministry in late December confirmed an initial report of the men’s detention in the German regional press.
Reports said they had hired a boat and sailed to an island near the straits of Hormuz, the entrance to the Gulf from the Indian Ocean.
A source close to the case in Paris said that “the French skipper had not been aware that they were entering Iranian territorial waters or a prohibited zone.”
The German foreign ministry spokesman said the German was under arrest in a private house and was “being treated well”.
“A representative of the German embassy in Tehran will be present at the opening of the trial,” he added.
A spokesman for the Iranian foreign ministry, Hamid Reza Asefi, earlier on Tuesday said the two would go on trial “if necessary”, depending on the opinion of the judges who investigated the case.
“They are safe and sound,” he said, adding that the men had access to their respective embassy representatives.
