ROME, April 14 -- Some 400 migrants including many minors could have died at sea over the weekend while attempting the crossing from Libya to Italy, Save the Children, the children's charity, said in a statement released on Tuesday.

The charity organization collected accounts from a group of around 150 survivors who were rescued by the Italian navy and transported to the southern city of Reggio Calabria.

Save the Children said more than 5,100 migrants have arrived on the Italian coasts between Saturday and Monday. Among them there were also some 450 children, 317 of whom not accompanied by adults.

"Many of them have suffered or witnessed atrocious experiences of violence and have lost friends, relatives or parents," CEO at Save the Children in Italy Valerio Neri said in the statement.

Neri described the situation in Libya as "increasingly out of control" with "inconceivable violence also on the streets."

"We lived for four months in a sardine factory near Tripoli. We were more than 1,000 people. We ate only once a day ... if someone tried to talk with a friend or anyone, he would be beaten," a 17-year-old witness told Save the Children.

The organization called on Italy and the whole European Union (EU) to face the growing emergency with adequate search-and-rescue operations and reception centers.

According to Italian authorities, most of the migrants saved in recent days were from Sub-Saharan countries such as Eritrea, Somalia, Ethiopia and Syria.

Nine of them were found dead on a craft some 130 km off northern Libya on Monday in an operation that involved various Italian maritime forces and a patrol vessel of Triton, a mission coordinated by the EU border control agency Frontex.

Launched last November, Triton was planned on a smaller scale compared to the previous one called Mare Nostrum (Our Sea) that Italy had put in place since the end of 2013 after hundreds of migrants died in two shipwrecks off the southern tiny island of Lampedusa.

At least 218,000 migrants tried to cross the Mediterranean Sea last year to try to enter the EU from its southern borders, and some 3,500 of them lost their lives in the attempt, the Refugee Agency of the United Nations (UNHCR) said in a recent statement, adding that the trend is "expected to continue."