The Swiss unit has also been a source of embarrassment lately for Stuart Gulliver, the chief executive of the parent bank, after revelations that he had used an HSBC Private Bank account to park 5 million pounds, or about $7.5 million, through a Panamanian vehicle. Mr. Gulliver has explained that he did so to hide his bonus from co-workers.

The parent company, HSBC, which is based in London and is Europe’s largest bank by stock-market value, in a statement on Friday sought to play down the importance of the French prosecutor’s move.

“This is a normal step in the judicial procedure, and the outcome of the matter is not determined as of today,” the bank said.

The accusations trace to 2007, when a whistle-blower named Hervé Falciani took files containing information on thousands of HSBC Private Bank accounts and handed them to the French government. Those same files ultimately served as the source of the data behind a report last month in which the International Consortium of Investigative Journalists and other news outlets published files that appeared to show HSBC Private Bank working aggressively to enable tax evasion in the period 2005 to 2007.

Two French investigating judges, Guillaume Daïeff and Charlotte Bilger, in November placed the Swiss unit under formal investigation. The prosecutor’s recommendation that the case go to trial was made on Tuesday, and was first reported on Friday by the French news organization Le Monde.