Italian investigators have overheard leading organisers of the people-trafficking that ended with thousands of deaths in the Mediterranean mocking the dire predicament of the people whose exploitation has made them millionaires, according to the UK's Independent newspaper.

Thirty-four-year-old Eritrean, Mered Medhanie, known as “The General” and based in Tripoli, boasted about the overcrowding of migrants on boats that set off from the North African coast to Italy.

“They say I put too many aboard, but they’re the ones who want to leave in a hurry,” he said, laughing, according to reports of wiretap evidence.

A second trafficker, who is said to have carved up much of the lucrative trade with Medhanie, declared last summer of some of his apparent paying customers: “They organised another trip a few days ago. I don’t know what happened – they probably died.”