Nelson Mandela's ex-wife Winnie expressed "surprise and shock" that prosecutors are considering charges against her following the exhumation of bodies believed to belong to two young activists last seen at her home 24 years ago.

In a statement from her lawyer dated Saturday and received Sunday (local time), Winnie Madikizela-Mandela said it is "difficult to legally imagine how and what new evidence is contemplated" given the many diverse accounts presented more than 10 years ago to South Africa's Truth and Reconciliation Commission.