Authorities in Niger have destroyed safe houses owned by human trafficking networks for sheltering illegal migrants and forcibly turned back anyone without a valid identity document in towns near its **rthern border, a government minister said on Thursday. The government has promised to ***** down on smuggling gangs ferrying people across the desert after 92 migrants died trying to make the same trip **rth to Algeria last year, many of them headed for Europe. The start of the summer migration season has seen a dramatic rise in the number of illegal migrants crossing the Mediterranean to Italy from the **rth coast of Africa. Many of these cross the Sahara desert via Niger to reach the Libyan coast, where they embark.