Big tech companies such as Alphabet and Facebook are stifling competition and need to be broken up, a leading digital media expert warned on Tuesday.

As those industry titans monopolize the internet and diversify their businesses, their neutrality is coming under scrutiny, Jonathan Taplin, director emeritus of the Annenberg Innovation Lab at the University of Southern California, told CNBC's Akiko Fujita at the CLSA Investors' Forum in Hong Kong.

Taplin, a former vice president of media mergers and acquisitions at Merrill Lynch, pointed to the European Union's milestone decision to fine Google $2.7 billion over antitrust abuses as an example.

Regulators found the search engine giant was favoring its own recommendations over third parties such as Yelp, he said.

"This is going to be a problem more and more as Amazon, for instance, gets into the business of manufacturing its own products. Amazon is going to push its own products over the third parties that it supposedly is a neutral seller for," Taplin told CNBC.