France on Wednesday said it would push ahead with its law to tax tech giants that has sparked a row with the United States, saying that an international accord was the only way to solve the dispute.

French Finance Minister Bruno Le Maire met US Treasury Secretary Steven Mnuchin on the sidelines of the meeting of finance ministers from the world's seven most developed economies in Chantilly outside Paris.

The EU's powerful antitrust authority launched an in-depth investigation into Amazon on Wednesday, amid suspicions the US-based online behemoth misuses merchant data hosted on its website.

The formal investigation opens a new chapter in the European Union's campaign to address the dominance of US tech firms with Google, Facebook and Apple also regular targets of regulators in Brussels.

With its probe, the EU competition watchdog is seeking to expand its oversight powers to data, the most prized asset for Silicon Valley giants that now dominate web-use worldwide.

"I have... decided to take a very close look at Amazon's business practices and its dual role as marketplace and retailer (and) to assess its compliance with EU competition rules," the EU's anti-trust commissioner Margrethe Vestager said in a statement.

As the public and government regulators around the world discuss whether and how to manage the power of technology companies, one idea that keeps coming up is breaking up these large conglomerate corporations into smaller pieces. Public distrust for tech companies has shifted to talk of antitrust action against them. Facebook, for instance, might then have to compete with Instagram for photo-sharing and WhatsApp for messaging – rather than owning both.