The head of the International Committee for the Red Cross has met US President George W Bush to discuss concerns about detainees at Guantanamo Bay.
Some inmates have complained of physical abuse
Jakob Kellenberger and Mr Bush talked about "ICRC concerns regarding US detention", the organisation said.
ICRC officials regularly visit the US naval base in Guantanamo Bay, Cuba, where suspected al-Qaeda and Taleban members are being held.
A leaked report by the ICRC was said to have found evidence of torture tactics.
The committee said Mr Kellenberger had met President Bush in Washington on Monday.
Their discussion "focused on ICRC concerns regarding US detention" as well as the main challenges facing the organisation in armed conflicts around the world.
He also met US Secretary of State Condoleezza Rice and is due to meet Defence Secretary Donald Rumsfeld on Tuesday.
'Tantamount to torture'
The Geneva-based agency said it welcomed the opportunity to "raise these issues at the highest level and looks forward to strengthening its confidential dialogue with US authorities."
The Bush administration insists the 540 or so inmates of Guantanamo - many of whom have been held without charge since the 2001 invasion of Afghanistan - have been treated humanely.
Human rights organisations say prisoners have been mistreated, and released detainees have spoken of beatings and coerced confessions.
Last November, media reports quoted a leaked ICRC report, from a visit last summer, as saying practices at the camp were "tantamount to torture".
The ICRC, which normally refuses to comment publicly on its work to help victims of conflict, refused to "publicly confirm or deny" the reports.