Around 300 others were rescued by Libyan coastguard, and are reported to have been taken back to Tripoli.
The migrants were travelling in two boats near Garabulli, east of Tripoli, one of which had already sunk when the coastguard arrived at the scene.
Children are reported to be among the dead.
Libya is the main departure point for migrants seeking to reach Europe through the Mediterranean Sea.
People smugglers have taken advantage of the country’s unstable political situation that has created a void in governance.
The UN Migration Agency, International Organization for Migration, reports that 161,010 migrants and refugees entered Europe by sea in 2017 through 24 November, with about 75 per cent arriving in Italy and the remainder divided between Greece, Cyprus and Spain. This compares with 345,831 arrivals across the region through the same period last year.
The agency’s Missing Migrants Project (MMP) has recorded the deaths of 5,080 people migrating in 2017.