Emails written by Facebook's chief and his deputies show the firm struck secret deals to give some developers special access to user data while refusing others, according to MPs.
A cache of internal documents has been published online by a parliamentary committee.
It said the files also showed Facebook had deliberately made it "as hard as possible" for users to be aware of privacy changes to its Android app.
Facebook had objected to their release.
It said that the documents had been presented in a "very misleading manner" and required additional context.
The emails were obtained from the chief of Six4Three - a software firm that is suing the tech giant - and were disclosed by the Digital, Culture, Media and Sport Committee as part of its inquiry into fake news.
About 250 pages have been published, some of which are marked "highly confidential".
Damian Collins MP, the chair of the committee, highlighted several "key issues" in an introductory note.
He wrote that:
- Facebook allowed some companies to maintain "full access" to users' friends data even after announcing changes to its platform in 2014/2015 to limit what developers' could see. "It is not clear that there was any user consent for this, nor how Facebook decided which companies should be whitelisted," Mr Collins wrote
- Facebook had been aware that an update to its Android app that let it collect records of users' calls and texts would be controversial. "To mitigate any bad PR, Facebook planned to make it as hard as possible for users to know that this was one of the underlying features," Mr Collins wrote
- Facebook used data provided by the Israeli analytics firm Onavo to determine which other mobile apps were being downloaded and used by the public. It then used this knowledge to decide which apps to acquire or otherwise treat as a threat
- there was evidence that Facebook's refusal to share data with some apps caused them to fail
- there had been much discussion of the financial value of providing access to friends' data
I believe there is considerable public interest in releasing these documents. They raise important questions about how Facebook treats users data, their policies for working with app developers, and how they exercise their dominant position in the social media market.
End of Twitter post by @DamianCollins
Facebook said Six4Three had "cherry-picked" the documents and claimed they had omitted "important context".
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"We stand by the platform changes we made in 2015 to stop a person from sharing their friends' data with developers," said a spokeswoman.
"Like any business, we had many internal conversations about the various ways we could build a sustainable business model for our platform.
"But the facts are clear: we've never sold people's data."
Mr Zuckerberg has also posted a personal response on his Facebook page.
"I understand there is a lot of scrutiny on how we run our systems. That's healthy given the vast number of people who use our services around the world, and it is right that we are constantly asked to explain what we do," he said.
"But it's also important that the coverage of what we do - including the explanation of these internal documents - doesn't misrepresent our actions or motives."
Tactics revealed
The correspondence includes emails between Facebook and several other tech firms, in which the social network appears to agree to add third-party apps to a "whitelist" of those given permission to access data about users' friends.
This might be used, for example, to allow an app's users to continue seeing which of their Facebook friends were using the same service.
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