The photos of Khalid Sheikh Mohammed were taken six years apart
The first images of alleged al-Qaeda mastermind Khalid Sheikh Mohammed at Guantanamo Bay have appeared on the internet.
Mr Mohammed appears with a long beard and wearing a white robe in the photos, taken in July by the Red Cross at the US detention centre in Cuba.
In February the US military began to allow the Red Cross to take pictures of inmates to send to their families.
Mr Mohammed had admitted planning the 9/11 attacks, the US military says.
Apart from courtroom sketches made during Mr Mohammed's hearings, these are the first images of him to emerge since a widely distributed picture taken upon his capture in Pakistan in March 2003.
The International Committee of the Red Cross said it took the most recent photos in July.
It said the pictures were sent to Mr Mohammed's family and were not intended for public release.
But the images have appeared in recent days on extremist websites, according to Jarret Brachman, former research director at the Combating Terrorism Center of the West Point US Military Academy.
He said the images - which emerge on the eve of the eighth anniversary of the 9/11 attacks - could inspire extremists.
"What's problematic for me is it really humanises the guy," Mr Brachman told AP news agency.
Mr Mohammed's trial is currently on hold while President Barack Obama, who has said he wants to close the Guantanamo detention centre by January, decides how to continue military prosecutions for some detainees.