Ninety per cent of refugees and migrants crossing the Sahara in the hope of reaching Europe have seen fellow migrants murdered, beaten or drop dead of exhaustion during their nightmarish journeys, a humanitarian organisation said on Tuesday.

Doctors for Human Rights, an Italian humanitarian group, based their findings on interviews with 1,000 African migrants who trekked across the desert to Libya and from there paid smugglers for their passage across the Mediterranean in ex-fishing boats and rubber dinghies.

Nine out of 10 migrants said that they suffered violence, torture or arbitrary imprisonment during their months-long journeys from West Africa and the Horn of Africa to the Libyan coast.

“You are no longer considered a human being on this journey,” one migrant told doctors. Aside from bearing the physical scars of their experiences, many are also suffering from what doctors described as a “hidden epidemic” of trauma, anxiety, depression and other psychological problems.

“It is no exaggeration to say that in Italy, there is a sort of hidden epidemic which requires adequate medical, social and cultural responses,” the organisation said in a report. “Extreme traumas such as torture and repeated violence are, tragically, a common experience during the journey from sub-Saharan Africa to Europe. Nine out of 10 migrants say they have seen someone die or be killed, tortured or badly beaten.”