More than 300 migrants are believed to have perished in the Mediterranean's frigid waters during their attempt to cross the sea in four rubber boats.

USA Today reported the vessels tried to make the journey from Libya to the Italian coast, according to the U.N. High Commissioner for Refugees (UNHCR). The suspected deaths are in addition to the 29 people who died from hypothermia Sunday on one of the boats.

The victims, some as young as 12, were "swallowed up by the waves," Carlotta Sami, the UNHCR's spokeswoman in Italy, said.

Survivors reported that the four boats left together with no food or water and began taking on water almost immediately. Some 107 people rescued by the Italian coast guard and a merchant ship were brought to the Italian island of Lampedusa, according to BBC.

"We know what fate we are going towards and the probability of dying. ... But it is a sacrifice we consciously make to have a future," one survivor told International Organisation for Migration staff in Lampedusa, Reuters reported.

According to the BBC, the United Nations said the incident should be a message to the European Union that the current search and rescue operations in the Mediterranean are inadequate.

"This is a tragedy on an enormous scale and a stark reminder that more lives could be lost if those seeking safety are left at the mercy of the sea," UNHCR official Vincent Cochetel said. "Europe cannot afford to do too little too late."

The tragedy reignited criticism of Italy's decision to end a full-scale search and rescue mission in an effort to discourage illegal immigration, Reuters noted.

Prime Minister Matteo Renzi, meanwhile, claimed the disaster highlighted the state of near-anarchy in Libya, a former Italian colony, where smugglers can charge up to $2,000 for the crossing.

"For months, for years, Libya has been totally out of control," he said in an interview with SkyTG24 television.

Renzi promised to bring the issue up at this week's meeting of European Union leaders in Brussels.