The Justice Department is purportedly investigating the Southern Poverty Law Center in connection with the group's use of paid informants to infiltrate extremist organizations decades ago. 

The group has acknowledged using such informants to infiltrate extremist groups and gather intelligence on their operations, which it shared with local and federal law enforcement, according to the Associated Press. 

The Justice Department had no immediate comment, the wire service also said.

Bryan Fair, CEO of the SPLC, said that the organization doesn't know all the details, but the Trump administration has launched an investigation, which may lead to charges. Fair said the SPLC worked with informants during the height of the Civil Rights Movement, when violence against activists was running high. 

He said the SPLC will "vigorously defend" themselves.