The Italian coast guard discovered 25 bodies on a boat on the southern island of Lampedusa, near Sicily. The men, who were refugees from Libya, died by asphyxiation when the air in the boat's hold became polluted by exhaust fumes.

The 50-foot boat was carrying nearly 300 people from Libya to Italy, said Coast Guard Captain Antonio Morana.The men tried to go above deck to breathe, but the boat was so packed they couldn't move before they collapsed and died, according to the Boston Globe.

"From what they told us upon arrival, there was no air to breathe, apparently they were so crammed there was nowhere to go," Laura Boldrini, spokeswoman in Italy for the U.N. High Commissioner for Refugees, told The Associated Press.

Authorities discovered the bodies when they unloaded the boat in Lampedusa. The island is closer to Africa than it is to mainland Italy, and is a frequent stopping ground for African migrants heading into Europe.

An estimated 20,000 African refugees fleeing the conflicts in Libya and northern Africa have sailed to Italy in recent months. Hundreds of people are believed to have died on way through the Mediterranean since the start of the year.

The boat set sail from Libya two days before it arrived in Lampedusa. It is said to be carrying mostly people from sub-Saharan Africa, including about 50 Somalis fleeing the famine and anarchy in their country. Survivors were taken to an immigrant shelter on the island.

Many sub-Saharan Africans have moved to Libya for work in recent years, but the civil war in the country has left them without a job and in a dangerous predicament.

In April, a boat carrying 300 Libyans capsized on its way to Italy, killing 250 people.