The centers, he told ANSA Friday on the sidelines of the Med Dialogues conference in Rome, are managed ''by the authorities and unfortunately also by other militias. We have convinced authorities to release about 1,000 people, who were actually refugees, from the detention centers, and we are working on at least 2,000 others. I believe that we are making progress. It takes a long time and working in Libya is not easy. It is a job that will take a long time.''

 UNHCR has long denounced situation at detention centers

A recent CNN investigation on migrants sold as slaves in Libya refers to ''situations that we have been speaking about for a long time,'' Grandi said. However, ''I think that it has the merit of sparking indignation and debate'', as well as ''concrete measures, such as the task force'' approved at the Abidjan summit between the African Union, the European Union and the United Nations. In addition, it has prompted ''measures that we are beginning to take in Libya to secure greater access to migrants and refugees and to offer them solutions, either in Libya or elsewhere''.The situation in the North African country ''is still difficult, fragmentary from an institutional standpoint, dangerous from the point of view of security, but progress is being made. Italy has provided a great deal of support,'' Grandi added.

 A new transit center for refugees

 ''We intend to open a transit center at least for those who need international protection'', for which ''we have received authorization from the Libyan authorities'', he said.These measures ''are small steps, but important starting points for work that we hope will have a positive impact on these tens of thousands of people trapped in these desperate situations.'' Grandi added that ''it is important that everyone understands that migration flows and especially that of refugees, people fleeing conflicts and persecutions and who cannot go home must be managed in a holistic manner, starting from their countries of origin to try to resolve the causes that are at the root of the movements, by the countries that host the largest number of refugees - generally African and Middle Eastern countries - transit countries and countries of destination.'' The response to these flows, he said, ''cannot come from a single country. The responsibility cannot be given only to countries of asylum. It must be the result of a coalition of international forces and this is why the task force is a positive step forward in dealing with the Libyan issue as well as that of flows in general''.