The drowning of 500 Middle Eastern and African migrants in the Mediterranean was no accident, according to survivors of the disaster, who have told an international humanitarian agency smugglers purposely sank their vessel and then laughed as men, women and children slipped below the waves.

The International Organization for Migration, a Geneva-based international organization with 156 member countries, is probing the claims, which, if true, underscore the cruelty that often accompanies desperation of immigrants seeking a better life in Europe. Witnesses said enraged human traffickers rammed their boat into the crowded vessel carrying the migrants after the travelers refused to transfer to a boat they considered unseaworthy, survivors told IOM.

Survivors reported the smugglers were "throwing metal bars" at the migrants and "laughing" as they struggled to stay afloat in the water, IOM spokesperson Leonard Doyle told FoxNews.com.

"If survivors' reports are confirmed, this will be the worst shipwreck of migrants in years, not an accidental tragedy, but the apparent deliberate drowning of migrants by criminal gangs who extort money for their desperate journeys. Their actions are as callous as they are evil," Doyle said in a statement.

Doyle said his group has so far confirmed 10 survivors -- two currently in Italy, two in Malta and six in Crete, including a toddler, who remains hospitalized in critical condition. Witnesses told the group that about 100 children were on board when the vessel sank on its way from the port of Damietta in Egypt to Italy.

The migrant boat -- with the Arabic name "Ashor Rezeq" -- departed Egypt on Sept. 6. The travelers were forced to transfer vessels several times throughout the journey but eventually refused a smaller boat they deemed unsafe for sea, witnesses said. Their vessel was then rammed by the traffickers' boat just off the coast of Malta. The 500 on board included Syrians, Palestinians, Egyptians and Sudanese.

Two Palestinian men who survived the shipwreck and were later brought ashore to the town of Pollazzo in Sicily told IOM the smugglers' vessel hit their boat twice on the side, causing the boat to flip.

"Most of the passengers were young, the majority under 30 years old and there were many families with young children," the men, ages 27 and 33, told IOM, according to Doyle.

"Migrants had to have bought life jackets themselves before the journey and few had brought them with them. Many of those with life jackets drowned also," the men said, adding that the smugglers did not offer life jackets to any migrants on board.

Doyle said a young Syrian woman was travelling with her fiancé, who drowned. The woman managed to cling to a round, donut-shaped buoy when she fell into the water and shared it with three children in an attempt to save them.

Two of the children drowned, Doyle said, but the woman managed to save a 2-year-old girl who is now hospitalized in Crete with kidney failure.

This could be the deadliest year ever for migrants crossing the Mediterranean Sea.

In the past week, as many as 700 people who were fleeing Africa for Europe died after two heavily loaded boats were wrecked. That's as many migrants as died during all of last year.

According to IOM and other officials, it would raise the total number of migrants killed on the Mediterranean this year to about 2,900.

In addition to the 500 migrants, another 200 are feared dead in the wreck of a second boat that was carrying at least 250 African migrants to Europe when it capsized off the Libyan coast.

With the surge of conflicts in the Mideast and Africa this year, more migrants are attempting the risky voyages across the Mediterranean in hopes of getting to Italy's coastline and islands.

FoxNews.com's Cristina Corbin and the Associated Press contributed to this report.