Libyan coastguards stopped 200 migrants shortly after their rickety boat carrying them to Italy left Tajura, near Tripoli, officials said on Sunday.
Libya, a popular departure point for African migrants trying to reach Europe, signed a new accord with Italy in February to strengthen their efforts to stem the flow of illegal migration to southern Europe.
"We stopped the boat and towed it to the shore and the migrants are being provided with the required humanitarian assistance by the authorities," a senior coastguard official told Reuters.
Another official said the migrants were from Niger, Nigeria, Ghana and Mali.
"They were crammed into the boat which barely can carry 60 people," the official added.
Both officials could not say whether the migrants would be detained and deported home.
Hundreds of thousands of illegal migrants from various African countries live in Libya, taking odd jobs until they earn enough money to pay smugglers for a place on a boat that will try to take them to Italy, always a risky venture, Libyan officials say.