European watchdogs today announced a wide ranging probe into how Silicon Valley giants use Apple's Siri, and Amazon's Alexa voice assistants to gather data on the public.
A day after losing a key court case on tax against Apple, EU competition commissioner Margarethe Vestager declared she was turning her fire back on Silicon Valley, also throwing in Google's recently-bought health tracking giant Fitbit.
She is also examining more widely how big companies use information gleaned through the so-called Internet of Things - the ability to communicate remotely with fridges, washing machines, smart TVs and other household goods.
The concern is that tech giants are keeping hold of data on customers to themselves for financial gain or potentially creating products and standards that do not work well with equipment made by other companies.
The EU will also investigate whether there is a prospect of Alexa, say, recommending customers buy certain favoured items from its owner Amazon when they use it for shopping.
Vestager said voice assistants generally only offer one option when you ask them for something, unlike the range of products you are offered when standing in a shop. That could give Apple, Amazon or Google an extremely powerful position over suppliers.
She said: "Access to large amounts of user data appears to be the key for success in this sector, so we have to make sure that market players are not using their control over such data to distort competition, or otherwise close off these markets for competitors."
She said "interoperability" was key - the ability of all suppliers' goods to be able to interact with each other rather than one powerful player creating its own standards to the exclusion of others.
Similar issues have raised concerns over smart cars, but that is being separately investigated and is not part of the new probe.
The EU said voice assistants could "lead to the fast emergence of dominant digital ecosystems and gatekeepers" who might favour certain suppliers.