Washington DC - A former executive of a prominent US civil rights organization was arrested on Wednesday for her alleged role in the use of donor money to secretly pay confidential informants in extremist groups, officials said.

Heidi Beirich, the former director of intelligence for the Southern Poverty Law Center, is charged with wire fraud, conspiracy to submit false statements to a bank, and conspiracy to commit money laundering, FBI Director Kash Patel said.

The Trump Justice Department indicted the Alabama-based SPLC, whose stated mission is to fight white supremacy and create a multiracial democracy, in April, and the charges against Beirich are contained in a superseding indictment unsealed on Wednesday.

Patel, in a post on X, said the SPLC "knowingly misled donors, who believed their money was being used to dismantle violent extremist organizations."

"In fact, part of those donations were instead being used to pay senior leadership within those extremist groups," he said.

Attorney General Todd Blanche said Beirich is alleged to have been "part of the effort to open bank accounts in completely fictitious companies' names and make payments to individuals for reasons that were not accurate."

The SPLC has acknowledged that it used confidential informants in the past to gather intelligence on extremist groups such as the Ku Klux Klan and National Socialist Party of America, but said it no longer does so.

The SPLC has also said that it shared information obtained from informants with local and federal law enforcement.

Michael Porter, Beirich's lawyer, said in a statement to US media that the case against his client is "without merit."

"We believe the charges against her and the SPLC are politically motivated, and Dr. Beirich has been targeted in this case because of the important work she has done to combat hate groups and extremists," Proctor said.

"Violent extremists have not stopped or intimidated Dr. Beirich from her vital work during her time at the SPLC," he said. "Dr. Beirich won't be silenced or intimidated by the government's false and politicized allegations now.

President Donald Trump has been accused by critics since taking office for a second time of launching criminal investigations of individuals and groups he sees as political or ideological opponents.