Libya's coastguard intercepted 137 migrants including five women and three children on Sunday as they attempted to reach Europe, a migration official told AFP.
Amine al-Boussefi, head of a government agency in Tripoli tackling clandestine migration, said "137 migrants were successfully rescued by the coastguard... then handed over to us".
The migrants, from several African countries, were aboard an inflatable boat intercepted Sunday morning around 40 kilometres (23 miles) north of Sayyad, a seaside village west of Tripoli, navy spokesman General Ayoub Qassem said.
The migrants were taken to a navy base in the capital where the Libyan authorities gave them food, water and medical treatment, an AFP photographer said.
They were then transferred by bus to the eastern Tripoli suburb of Tajoura and handed over to the anti-migration agency.
The AFP photographer saw dozens of migrants gathered in a courtyard there, sitting on the ground under the blazing sun as they waited to be put in detention centres.
Six years since a revolution that toppled dictator Moamer Kadhafi, Libya has become a key departure point for migrants risking their lives to cross the Mediterranean to Europe.
Hailing mainly from sub-Saharan countries, most board boats operated by people traffickers in the country's west, heading for the Italian island of Lampedusa 300 kilometres (190 miles) away.
More than 111,000 migrants have reached Europe by sea so far this year, the vast majority of them arriving in Italy, according to the latest figures from the International Organization for Migration.
Over 2,300 have died attempting the crossing.