As many as 30 to 40 foreign prisoners have been held at the camp in Iraq at any given time, military officials said; they did not provide an estimate for the Afghan camp but suggested that the number was smaller.
The ICRC is allowed access to almost all American military prisons and battlefield detention sites in Iraq and Afghanistan, but the Special Operations camps have been excluded.
A spokesman for the ICRC in Washington, Bernard Barrett, declined to comment on the new notification policy, citing the organisation's longstanding practice of refusing to talk about its discussions with the defence department about detention issues.
The New York Times reported in 2006 that some soldiers at the temporary detention site in Iraq, then located at Baghdad international airport and called Camp Nama, beat prisoners with rifle butts, yelled and spit in their faces, and used detainees for target practice in a game of jailer paintball.
Military officials say conditions at the camps have improved significantly since then, but virtually all details of the sites remain shrouded in secrecy.
The US military had previously insisted that disclosing any details about detainees at the secretive camps could tip off other fighters and jeopardise counterterrorism missions.
Separately, Eric Holder, the US attorney-general, is expected to decide in the next several days whether to appoint a criminal prosecutor to investigate the interrogations of suspects accused of being involved in terrorism after the attacks of September 11, 2001.
The new Pentagon policy on detainees took effect this month with no public announcement from the military or the ICRC.
It represents another shift in detention policy by the Obama administration, which has already vowed to close the US military prison at Guantanamo Bay, Cuba, by next year and is conducting reviews of the government's procedures for interrogating and detaining fighters.