Government sources told journalists it was unlikely that Le Roux could remain in the government and the PNF fraud office announced on Tuesday it had opened a preliminary investigation, which could lead to a full inquiry such as that Fillon's Penelopegate affair.
Cazeneuve appeared to distance himself from Le Roux, who succeeded him at the interior ministry, with a declaration that people invested with the authority of the state had to be "impeccable in relation to its institutions and the rules that cover them".
Le Roux himself attended a session of the Senate but cancelled at least two appointments on Tuesday,
Daughters employed while studying
The Quotidien programme on the private TMC channel has revealed that the minister, who used to head the Socialist parliamentary group, employed his two daughters on short-term contracts 14 times in one case and 10 in the other between 2009 and 2016.
They are believed to have been paid a total of 55,000 euros in salaries.
They were school students of 15 or 16 years old when they first worked for their father and did so while at school and later at college.
It is not illegal for French politicians to employ their relations and Le Roux told TMC his daughters were working during their summer holidays.
Quotidien did not establish that their jobs were fake - the accusation that has led to Fillon being charged with misuse of public funds - although it said that the elder daughter was on an internship in with cosmetics company Yves Rocher in Belgium during one period of employment in 2013 and the other was employed at least once during the university term.
Politicians react with caution
While Foreign Affairs Minister Jean-Marc Ayrault said that "everyone must receive the same treatment" and called for "transparency and exemplary behaviour", Socialist Party national secretary Jean-Christophe Cambadélis stressed that "nothing for the moment allows us to say that these are fake jobs" and pointed out that Ler Roux is not standing for president.
The government's right-wing opponents, whose presidential candidates are being investigated for alleged corruption, seemed hesitant to seize on the story, Bernard Accoyer of the mainstream right Bernard Accoyer saying "Let's wait for more details."
National Front vice-president Florian Philippot speculated that "He might have to resign or be resigned."
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