The news was first reported by the Wall Street Journal, which said Irelands data commission gave Facebook until mid-September to respond to a preliminary order to suspend the transfers.
The Irish data commission suggested that a type of legal mechanism governing the data transfers, known as standard contractual clauses, cannot in practice be used for EU-U.S.
The commission, which did not reply to a request for comment, is Facebooks lead privacy regulator in Europe and can fine companies up to 4% of annual revenue for data breaches.
Its the first major move by a European regulator after the EUs top court issued a ruling in July on the two types of legal mechanisms used to govern data transfers.
The European Court of Justice invalidated an agreement known as Privacy Shield and decided that the standard legal clauses were still OK.
Its the latest development in a case that originated more than seven years ago, when Max Schrems, an Austrian privacy activist, filed a complaint about the handling of his Facebook data after former U.S. National Security Agency contractor Edward Snowden revealed the American government was eavesdropping on peoples online data and communications.
In Facebooks case, for example, messages between Europeans would have to stay in Europe, which can be complicated and require the platform to be split up, Schrems has said. Original article