The French government has summoned Facebook managers to appear before the country's data watchdog to explain how some of its users came to believe their privacy had been infringed on the social network, it said in a statement early on Tuesday.
Two ministers said they had intervened after seeing reports that private messages between Facebook users in France had appeared on their "Timelines", which can reach a wide internet audience.
Metro newspaper reported that a "non-systemic" problem at Facebook had caused certain personal messages, some several years old, to be displayed on the Timelines which serve as a profile page with details selected by the user.
Facebook France denied any breakdown in its security systems and said that while some old data had appeared where it should not have, none of it originated from private messages.
"A minority of users were worried after seeing messages they thought to be private appearing on their Timelines," a spokesman for Facebook France said.
"Facebook engineers examined the situation and confirmed that the messages in question were old postings, which had previously been visible on the users' profiles," he added.
Announcing the appearance of Facebook bosses in front of the CNIL data privacy agency later on Tuesday, Industry Minister Arnaud Montebourg and Small Businesses Minister Fleur Pellerin called for "clear and transparent explanations" and said the episode demonstrated the need for better data protection.