In its final decision on the WhatsApp case, the commission also ordered the company to bring its data processing operations into compliance with EU privacy rules within six months.
WhatsApp said it disagreed with the decision and plans to appeal.
“We strongly believe that the way the service operates is both technically and legally compliant,” it said in a statement.
The Irish watchdog's decision was written in dry technical language but signs of the tension with its EU counterparts were evident in a section near the end, where it said that a board of EU data protection regulators “purported to direct" it to carry out a fresh investigation of all of WhatsApp's data processing operations.
It's not up to the board to “instruct and direct an authority to engage in open-ended and speculative investigation,” the Irish watchdog said, adding it would ask the EU's top court to annul the order because it's “problematic in jurisdictional terms."
This version corrects number of EU member countries to 27 in fourth paragraph.