Federal agents were recently told that the FBI would no longer investigate confrontations involving immigration officers, The New York Times reported Sunday, citing people familiar with the decision.
Such investigations can uncover evidence against Department of Homeland Security officers accused of using excessive force, according to the report.
If implemented, the move would significantly reduce oversight of immigration agents as the administration of US President Donald Trump faces growing criticism over fatal encounters involving federal officers, the report said.
FBI managers reportedly received written notice of the change Thursday, while some Immigration and Customs Enforcement (ICE) agents were informed by their FBI counterparts the same day.
The New York Times reported that the guidance said the bureau would no longer investigate alleged assaults on DHS agents, even though such inquiries often help determine what happened and can produce evidence implicating the officers themselves.
A joint statement from the Justice Department and the Department of Homeland Security denied that there had been any policy change, saying: "The relationship between D.H.S. and D.O.J. in investigating assault on federal officer cases has not changed, and F.B.I. will continue to investigate in accordance with agency policy."