The International Criminal Court’s prosecutor said Friday that she would request permission to open an Afghanistan investigation, a step that may lead to the court’s first indictments of Americans for war crimes.

The prosecutor, Fatou Bensouda, has been collecting information on the war in Afghanistan for years. She has suggested before that she has evidence for a prosecution — not only of allegations of atrocities committed by combatants in Afghanistan, including the Taliban, the Afghan armed forces and the United States military, but of related crimes in other countries where C.I.A. operatives once held and tortured Afghan prisoners.

Ms. Bensouda said she would ask the judges in the court, which is based in The Hague, for authorization to pursue a formal investigation. If they agree, the Afghanistan investigation and any resulting indictments could pose a legal test for the United States — which does not recognize the court’s jurisdiction — to cooperate with it, especially if any defendants are American.

“In due course, I will file my request for judicial authorization to open an investigation, submitting that there is a reasonable basis to believe that war crimes and crimes against humanity have been committed in connection with the armed conflict in Afghanistan,” Ms. Bensouda said in a statement.