Nobel Peace Prize winner Desmond Tutu has questioned why it took so long for South African prosecutors to charge former members of the apartheid-era security forces for the 1983 death of an activist.

On Thursday, Tutu welcomed the National Prosecution Authority's decision this week to prosecute four men linked to the torture and disappearance of 23-year-old Nokuthula Simelane.

Tutu, who led South Africa's Truth and Reconciliation Commission, questioned why prosecutors only acted after the young woman's family approached a court. He said the commission had already finalized the case in 2001.

After apartheid ended in 1994, the commission investigated past atrocities and granted amnesty to some accused perpetrators.

In his statement, the retired archbishop asked why only a "handful" of more than 300 cases recommended for prosecution were pursued.