The French prime minister's office has admitted to tipping off prosecutors about possible leaks to the website Mediapart - whose offices police attempted to search on Monday.
It's generated a major row about the journalists' right to keep their sources private - in a case that could prove very embarrassing to the French President.
Elena Casas reports from Paris.

EU calls on restraint in Venezuela
Trump says Venezuela's Maduro captured after strikes
Russian strike on Ukraine's Kharkiv kills two, injures 25
Two dead as strong earthquake hits Mexico
US says it thwarted potential IS-inspired New Year's Eve attack