Damian Collins used parliamentary privilege to outline the detail from the sealed documents, during a fiery session of questioning of Facebook executive Richard Allan before the first sitting of the "international grand committee on disinformation and fake news" in London on Tuesday.
The House of Commons digital, culture, media, and sport committee had gathered members from nine different national parliaments to get Facebook founder Mark Zuckerberg to face questions around data use and elections.
Allan and the chair of the committee had a spat over what's alleged to be in a set of documents that are subject to the protective order of a California court.
The documents had been obtained during discovery by the legal team of Ted Kramer, the managing director of app developer Six4Three, who is suing the social network.
Collins received the trove from Kramer and used a parliamentary mechanism to seize the sealed documents, which included emails between Facebook executives discussing the company's relationships to developers and data.
Collins said the emails would not be released. But he did outline details from an alleged incident which, if true, would raise further questions about how Facebook responded to learning about data being taken from the platform.
"An engineer at Facebook notified the company in October 2014 that entities with Russian IP addresses have been using a Pinterest API key to pull over 3 billion data points a day", Collins said.
Allan dismissed the claim by focusing on the source of the information, Six4Three, labelling it a "hostile litigant".
"There is, as I understand it, a partial set of information that was obtained by a hostile litigant who is repeatedly seeking to overturn actually the changes to restrict access to data that you as a committee and others would want us to see happen", he said.
The Facebook executive added: "Any information that you have seen in that cache of emails is at best partial, and at worst potentially misleading."
After the incident was aired in the committee, a Facebook spokesperson sent a statement to BuzzFeed News: "The engineers who had flagged these initial concerns subsequently looked into this further and found no evidence of specific Russian activity."