By Ahmed Elumami TRIPOLI (Reuters) - Libyan authorities have arrested three people on suspicion of involvement in launching a boat packed with migrants that sank off the country's Mediterranean coast, killing up to 200 people, a security official said on Saturday. Libya has turned into a main transit route for migrants fleeing conflict and poverty to make it to Europe. three Libyan smugglers involved in launching the ill-fated boat and other vessels to take migrants to Italy have been arrested, said a security official, asking **t to be named.