The Nobel Prize recipient was touring Europe with his wife Elita when he suffered bouts of dizziness, the South African daily newspaper Die Burger reported Tuesday.
De Klerk made a remarkable recovery from a severe lung infection he developed following colon surgery in 2006.
The former leader shared the 1993 Nobel Peace Prize with South Africa's first black President Nelson Mandela.
Charlize Theron not engaged to Sean Penn 'yet'
Pistorius testifies he didn't consciously pull trigger when he shot girlfriend