The head of the European Union’s border agency Frontex, Fabrice Leggeri, has offered to resign, a source said on Friday, after accusations the body mistreated migrants on the external frontiers of the bloc.

The EU’s anti-fraud agency OLAF launched an investigation last year into allegations of human rights violations by Frontex, an agency tasked with managing migration on the bloc’s external frontiers. OLAF’s report has not been made public.