The FBI cut ties to at least a handful of informants and issued warnings about dozens of others after an internal review prompted by concerns that they were linked to Russian disinformation, current and former U.S. officials said.

The review was carried out in 2020 and 2021 by a small group within the bureau’s counterintelligence division, with the findings then passed along to field offices, which handle informants.

It led to the severing of sources — some of whom had offered information about Russia-aligned oligarchs, political leaders and other influential figures — at a moment when the bureau was asking agents to produce more information from and about those same networks. The review was conducted during and after the 2020 election, when concerns about Russian meddling were running high, and at a time when the United States was closely monitoring whether Russia would invade Ukraine.