The Lockerbie bomber remains in hospital, where he is receiving a blood transfusion, it has been reported.
Abdelbaset al-Megrahi's health is said to have "deteriorated quickly".
His brother Abdulhakim told Reuters news agency that he was taken from his home in Tripoli, Libya, to a private hospital.
"His health began to deteriorate quickly and we were worried about him, so took him immediately to the hospital where he is receiving a blood transfusion," he said.
Megrahi is the only man convicted of the bombing, which killed 270 people when Pan Am Flight 103 blew up over Lockerbie, Dumfries and Galloway, four days before Christmas in 1988.
He was sentenced to life in prison in 2001, but was released on compassionate grounds from Greenock Prison, Inverclyde, in August 2009, after being diagnosed with terminal cancer.
At the time, doctors estimated he had around three months to live.