Technology companies Google and Twitter are distancing themselves from Facebook's operations in Australia ahead of a world-first inquiry into big internet platforms.

The Mark Zuckerberg-led Facebook has been thrown into crisis after it emerged data from 50 million worldwide users was harvested without their consent by Cambridge Analytica, a British-based research firm that helped Donald Trump win the US presidency.

Facebook Inc. shares posted their steepest drop since 2015 amid calls in the United States and Europe for far deeper regulatory scrutiny of the platform.

As a result of the scandal, the Australian Competition and Consumer Commission's inquiry into internet platforms is taking on a global significance. It is examining the influence of internet platforms, particularly the spreading of fake news stories and diverting advertising away from traditional media.

Other companies involved in the enquiry on Tuesday expressed concerns about being negatively associated with Facebook.