The EU will unveil proposals for a digital tax on US tech giants yesterday, bringing yet more turmoil to Facebook after revelations over misused data of 50 million users shocked the world, reports AFP from Brussels.

The special tax is the latest measure by the 28-nation European Union to rein in Silicon Valley giants and could further embitter the bad-tempered trade row pitting the EU against US President Donald Trump.

EU Economics Affairs Commissioner Pierre Moscovici will present proposals aimed at recovering billions of euros from mainly US multinationals that shift earnings around Europe to pay lower tax rates.

The transatlantic blow has been championed by French President Emmanuel Macron and will be discussed over dinner at an EU leaders summit on Thursday.

"This will be given top priority as tax file. There is a lot of political momentum on this issue," an EU official said ahead of the announcement. The unprecedented tech tax follows major anti-trust decisions by the EU that have cost Apple and Google billions and also caught out Amazon.

The commission's tax, expected to be about 3 percent of sales, would affect revenue from digital advertising, paid subscriptions and the selling of personal data.