It comes nearly two weeks after a boat carrying some 900 migrants capsized in the Mediterranean Sea while heading from Libya to Italy, resulting in the deaths of almost all on board, with only 28 rescued.
The demonstration by the Italian General Confederation of Labour (CGIL), the Italian Confederation of Workers' Trade Unions (CISL) and the Italian Labour Union (UIL) in Pozzallo began with a minute of silence in memory of migrants who have died in the Mediterranean.
"We have no words to describe what is happening right now in the waters of the Mediterranean Sea", CGIl General Secretary Susanna Camusso said, addressing the demonstrators.
She stressed that the present situation, when, according to Italy's Interior Minister Angelino Alfano, over 70,000 undocumented migrants are currently residing in immigration detention facilities across Italy, violates Article 10 of the Italian Constitution granting migrants a right to asylum in Italy.
Tens of thousands of undocumented migrants, often fleeing war-torn countries of origin, enter Italy across the Mediterranean Sea, their main route to Europe.
Last year, Italy's Mare Nostrum rescue mission, which helped some 150,000 immigrants to safely reach Europe via the Mediterranean, was suspended.
It was replaced by a pared back joint EU operation entitled Triton, which only patrols within 30 miles off the Italian coast and focuses on border surveillance instead of search and rescue missions.
Amnesty International said the death toll in the Mediterranean between January 2015 and mid-April was 100 times greater than in the same period of 2014, amounting to as many as 1,700 victims.
