Facebook has admitted that some European users had their chats accessed and transcribed without their knowledge | Loic Venance/AFP via Getty Images EU data caught in Facebook audio transcribing The social networking giant initially said no local users were affected, but 48 EU citizens had their information collected without their knowledge.

Facebook could face new privacy investigations after the social networking giant admitted that some of its European users had their audio chats collected and transcribed without their knowledge.

The revelation comes after Facebook had initially claimed that no one from the 28-country bloc had their audio messages collected and transcribed by hundreds of third-party contractors in a potential violation of the region's tough privacy standards.

Yet after reviewing the activity, which took place at the end of July and early August, the company has now told EU privacy regulators that roughly 50 Europeans in 14 countries were caught up in the activity, as they had sent audio messages on its online platforms to U.S. users who were involved in the transcription trial.

Typically, the Irish privacy regulator is responsible for Facebook's activities across the EU because the company has its international headquarters in Dublin. But because the latest privacy issues took place in the United States, and not Europe, regulators in each EU country are permitted to start their own probes because the activity falls outside the remit of Ireland's Data Protection Commission.

"All EU supervisory authorities in whose jurisdiction data protection violations against persons who have used Facebook Messenger have occurred are responsible for investigating the respective violations,” Johannes Caspar, the Hamburg commissioner for data protection, told POLITICO in an email. His agency has opened an investigation into Facebook’s collection of people’s data linked to the audio clips.

"An agreement has also been reached between the HmbBfDI and the IDPC in Ireland that the case must be taken over by the respective national data protection authorities," he added, in reference to the Hamburg and Irish privacy regulators.

Facebook said its transcription trial was not available in Europe, but confirmed that 48 of its EU users had snippets of their audio chats transcribed and reviewed by a third-party company.

Under Europe's new privacy rules, known as the General Data Protection Regulation, or GDPR, the company could face fines of up to 4 percent of its annual revenue if it is found to have broken the region's privacy rules.

Hamburg's privacy regulator has started an investigation and is working to clarify Facebook's activities in relation to collecting and transcribing EU citizens' audio chats without its consent.

The latest privacy issues facing the company comes after it was fined $5 billion by U.S. authorities over separate data protection issues. It also faces at least 10 ongoing privacy probes by Irish authorities in relation to how it complies with Europe's existing data protection standards.

This article has been updated with comment from Facebook.