Germany's president says his country's diplomats failed for years to act on human rights violations at a secretive colony of ethnic Germans in Chile.

President Joachim Gauck spoke Tuesday after meeting with Chilean President Michelle Bachelet in Santiago.

He says they spoke about "dark chapters" in their countries' past, referring to Colonia Dignidad, or Dignity Colony.

For three decades from 1961, the enclave was the site of torture, slavery and child abuse. Its history featured in a recent movie starring Emma Watson and Daniel Bruehl.

Germany recently ordered documents about the colony until 1996 to be unclassified for research purposes.