The United States imposed sanctions Thursday on Venezuela's military counter-intelligence agency, accusing it of torturing and murdering detainees.

The new sanctions, announced by the US Treasury Department, freeze any US-based assets of the country's General Directorate of Military Counterintelligence.

They come less than a week after the US imposed sanctions on President Nicolas Maduro's son, as part of Washington's bid to force the Venezuelan leader from power.

Treasury Secretary Steven Mnuchin said in a statement the move was triggered by the death in custody of a navy captain who was allegedly tortured.

"The politically motivated arrest and tragic death of Captain Rafael Acosta was unwarranted and unacceptable,” Mnuchin said.

The captain was arrested in June on charges of plotting to assassinate Maduro. He died in custody eight days later, and Venezuela's attorney general said that two officials from the counter-intelligence agency were charged with homicide.

The Treasury said that when Acosta appeared in court after his arrest, "he showed signs of physical abuse, including being in a wheelchair, and he was unable to speak."

It said that despite the arrest of two of the agency's officials in connection with his death, "this is only the most recent display of brutality undertaken by an agency notorious for its violent methods."

UN rights chief Michelle Bachelet said she was "shocked by the alleged torture of Captain Acosta Arevalo and that his treatment in custody may have been the cause of his death."

The latest US action comes as Maduro moves to consolidate his hold on power after what Caracas called a failed coup attempt by opposition leader Juan Guaido, who was recognized by Washington and some 50 other countries as Venezuela's legitimate leader.