Facebook wants a New York University research project to stop collecting data about the social platform’s political ad-targeting, The Wall Street Journal reported.

The Ad Observatory, a project of NYU’s engineering school with more than 6,000 volunteers, uses its AdObserver browser extension to scrape data from political ads shown on Facebook. But Facebook says the program is violates its terms of service, which bar scraping.

A Facebook official sent a letter to the Ad Observatory researchers October 16th, saying that “scraping tools, no matter how well-intentioned, are not a permissible means of collecting information from us.” The letter also threatened further enforcement action if the project did not shut down and delete the data it has collected, according to the WSJ. The company could change its own code to block the NYU team from collecting further data, a Facebook spokesperson told the WSJ.

The NYU group discovered this week that Facebook was not labeling all political ads to show who had paid for them as its own disclosure rules require, BuzzFeed News reported.

Last month, Facebook unveiled a list of new provisions it was putting into place to try to stave off election interference in the November 3rd US presidential election. It said it would stop taking political ads for a w