Bachelet said police were reported to have used excessive force, firing rubber bullets, using water cannons and throwing stun grenades.
"Reports suggest that more (than) approximately 6,000 people have been detained in the last three days, including bystanders, as well as minors, suggesting a trend of massive arrests in clear violation of international human rights standards," she said in a statement.Even more disturbing are the reports of ill-treatment during and after detention," she said, calling for the release of all those unlawfully detained and for investigations into abuses.