WASHINGTON (AFP) - A US civil rights group said that it plans to file a lawsuit against the CIA on behalf of a man who says he was abducted by the agency, beaten and transported to a secret prison in Afghanistan.

The American Civil Liberties Union (ACLU) said it would file the suit in court in Virginia on Tuesday in what it described as the first ever legal challenge to the alleged CIA practice of abducting foreign nationals for detention and interrogation in clandestine overseas prisons.

The plaintiff, an "entirely innocent victim" who was eventually released without charge, would attend a press conference the same day in Washington, the ACLU said.

The lawsuit charges that CIA officials at the highest level authorised agents to abduct the plaintiff, detain him incommunicado, beat him, drug him and transport him to a detention facility in Afghanistan.

It also argues that the corporations owning and operating the airplanes used to transport the man were legally responsible for assisting in the violation of his civil and human rights.

On Wednesday, a leading human rights monitor published the names of 26 "ghost detainees" that it accused the United States of holding and possibly torturing in secret overseas locations.

The prisoners, suspected of involvement in such acts as the September 11, 2001, attacks, the 1998 US embassy bombings in Kenya and Tanzania, and the 2002 nightclub bombing in Bali, Indonesia, are being held indefinitely and incommunicado, with no access to counsel, Human Rights Watch alleged.

Reports of clandestine CIA interrogation centers and transport flights for terrorist suspects emerged last month, along with suggestions of on-board torture sessions.

The US State Department said this week it would provide a timely and forthright answer to a European Union letter expressing concern over the reports.