By Nathan Morley
The boat had set sail east of the Libyan capital of Tripoli on Wednesday evening.
This sinking off the coast of Libya underscores the deadly risks facing those who attempt to make the perilous crossing.
Reports suggest that Libyan fishermen sighted the sinking vessel late Thursday and managed to pull 22 people from the water.
The International Organization for Migration said citizens from Egypt, Bangladesh, Syria, Somalia and Ghana were rescued.
However, at least 13 of the other passengers were missing and presumed dead. According to reports, three bodies were found at sea, including a Syrian man and woman. Authorities are scouring the area for more victims.
Following the fall of Libyan dictator Moammar Gadhafi, the country has emerged as the dominant transit point for migrants hoping to get to Europe.
Human traffickers often herd desperate families into flimsy rubber boats that capsize and founder along the perilous central Mediterranean route.
The UN says at least 20,000 people have died in those waters since 2014.
Earlier this week Tunisian authorities said that their naval patrols had intercepted a total of 19 boats carrying 246 migrants hoping to land in Italy.