At least 19 people were killed on Wednesday and more than 100 injured when a truck transporting African migrants crashed south of the Libyan town of Bani Walid, a hospital said.
More than 300 migrants, mostly Eritrean and Somali nationals, were on board.
A child was among at least 19 migrants killed in the accident, the head of the town's hospital, Salah al-Mabrouk, told AFP.
The hospital, which had earlier given a toll of 23 dead, said at least 124 migrants were injured and it was struggling to cope.
"Several victims are even being treated on the ground," said spokesman Salah al-Twijer.
Bani Walid, on the edge of the desert 170 kilometers southeast of the capital Tripoli, is a transit point for migrants heading to the Mediterranean coast.
They are often held and transported in brutal conditions, passed between smugglers who take payments for different stages of the journey and extort money from migrants.
From northern Libya, many of the migrants attempt to cross to Italy in flimsy inflatable dinghies.