Online platforms are under pressure in Europe because of their dominance and anti-competitive business practices, which have resulted in hefty fines handed down to some companies. Privacy and consumer concerns have also aggravated the situation.
Seven months after Europe's Justice Commissioner Vera Jourova told Facebook and other tech companies to bring their user terms in line with EU consumer laws, the social media giant has yet to address all her concerns, the sources said.
"There is only limited progress and this has been going on for too long," the sources said.
Jourova had previously voiced concerns about the companies' liability and how users are informed about content removal or contract terminations.
Consumer protection authorities across the 28-country bloc, which requested the changes last year, have the power to fine the companies for breaching EU rules.
Facebook has previously said it worked with EU authorities to amend its terms and ensure greater transparency.
Three months after being told to revise its terms and conditions, Airbnb has made the necessary changes, the sources said.
"This is good news for consumers who will benefit for instance from more transparency on prices, so they can compare offers upfront," the sources said.
The European Commission had told Airbnb to state whether accommodation is offered by a private individual or a professional, provide details of prices in a clear way and offer fairer terms to consumers.
Founded in 2008 in San Francisco, Airbnb matches people wishing to rent out all or part of their homes to temporary guests, via a website.
Jourova will hold a news conference on the issue at 0815 GMT on Thursday.