More than 300 deaths have been recorded in the Mediterranean Sea in the past week, due to irregular sea crossings by migrants from North Africa to Europe.
Almost 1,900 people have died in these type of incidents so far this year, with 1,600 deaths being since June.
Speaking to journalists, UNHCR senior spokesperson Melissa Fleming said: "The past few days have been the deadliest this year on the Mediterranean for people making irregular crossings to Europe, with at least three vessels having overturned or sunk."
On 15 August, a boat carrying 270 people overturned near Garibouli to the east of Tripoli, Libya, leaving only 19 survivors, with the remaining passengers feared drowned.
According to reports, the vessel was at full capacity and more people were pushed onboard before departure. This overloading trapped the people on the lower deck once the ship had flipped.
A second accident ocurred on 16 August, leaving 18 dead and ten missing around 20 miles from Libyan inland waters. The boat was carrying more than 100 people mainly from Mali, Côte d'Ivoire, Guinea and Sudan.
"UNHCR's Tripoli office receives daily calls from refugees, asylum-seekers and other vulnerable people expressing fear for their lives and making desperate requests for food, water, medicine and relocation," Fleming added.
"Those who choose to leave for Italy are taking longer and riskier journeys through new ports of departure such as Benghazi (in eastern Libya)."
In a third incident, a fishing boat capsized north of the Libyan coast on 17 August, killing 24 people and leaving 12 almost drowned.
Worsening security situations and conflicts, mainly in Libya, have encouraged refugees and migrants to risk the dangerous sea journey.