Business journal Les Echos said on Thursday the figures come from information leaked to the French government by Hervé Falciani, the former IT worker at the Geneva branch of HSBC Private Bank, a subsidiary of British-based HSBC.

Falciani, who was arrested in 2012 and subsequently released in Spain, where he cooperated with authorities, transmitted a list 127,311 names of potential tax evaders with accounts at HSBC in 2008.

Of these 2,932 individuals and “legal entities” are resident in France.

Switzerland has issued a request to extradite Falciani, who faces charges of violating Swiss banking secrecy laws, but he is now under police protection in France, where is also cooperating with authorities.

Earlier this month he testified behind closed doors to a French parliamentary committee.

Citing a report from French Socialist MP Christian Eckert on the Falciani list, Les Echos totted up the numbers and came up with the figure of almost five billion francs in assets held in HSBC accounts in Switzerland.

But only one in six of the French account holders declared their assets to tax authorities and only a quarter of the assets have been properly reported or “regularized”, the journal reported.

French tax authorities have so far only recovered €186 million (230 million francs) in owed taxes and penalties from the HSBC account list.

The Eckert report highlights that just one percent of French individuals or companies accounted for $1.75 billion of the assets in the Swiss accounts.

The report notes that 169 of HSBC’s 1,293 employees at the time when the information was initially leaked were residents of France, Les Echos said.

“It is probable that employees held accounts to the benefit of clients and played the role of front-man,” the report says.

In certain cases, the assets of employees exceeded 100 million francs, up to 500 million francs, Les Echos said.

In his report, Eckert denounced the slowness with which French tax authorities have dealt with the information from the Falciani list after launching a preliminary investigation in 2009.

The list contains tens of thousands of suspected tax evaders from around the world, including the UK, Spain, Germany and Greece.