moas phoenix
The M.Y. Phoenix, owned by the Migrant Offshore Aid Station (MOAS), has been credited with saving thousands of migrants in the Mediterranean SeaGIOVANNI ISOLINO/AFP/Getty Images

Almost 50 people are fear drowned at sea after Spain's maritime rescue service says three men were rescued from a boat.

Rescue services said that the three men from sub-Saharan Africa were rescued 28 miles (45km) southwest of the island of Alboran in the Mediterranean Sea between Spain and Morocco.

Authorities were alerted by an NGO aid worker who reported a vessel carrying 52 had set off from Al Hoceima on Sunday (2 July). The actual location was later discovered to be 40km east of the initial report.

A continuous search began in which the ocean was scoured for two days before what is thought to be the original vessel was found - a half-sunk rubber dinghy with only three disoriented men left on board.

A spokesperson for the coast guard told the BBC that it was likely the others had drowned at sea as the dinghy drifted off the Moroccan coast.

One of the survivors was a 17-year-old boy while the other two were 25-year-old men. All three have been taken to Almeria for medical care.

The BBC reported that if there were no further survivors, it could be the deadliest migration attempt in 2017. The International Organisation for Migration said in May that the number of people reaching Italy by boat had risen 40% from 2016 - some have turned blame towards NGOs, accusing them of acting as a ferry service and therefore aiding people smugglers.