Libya's internationally recognized government says Italian vessels entered the country's territorial waters without permission and vowed to use "all means" to protect its sovereignty.

It says three Italian vessels were spotted off the coast of the eastern city of Benghazi early Sunday. The ships are likely part of an international effort to stem the flow of migrants crossing the Mediterranean to Europe.

Last month, the U.N. authorized European Union countries to inspect vessels and use force to disrupt migrant smuggling on the high-seas off Libya, but not in its waters.

Libya slid into chaos following the 2011 toppling and killing of dictator Moammar Gadhafi. Smugglers have exploited the turmoil, sending tens of thousands of migrants off in rickety boats to Europe.