357 persons were returned Tuesday night to Libya, 90 to Tripoli and 267 to Zawiya, in 2 separate operations, according to UN High Refugee Agency (UNHCR).
54 women and 22 children were among the migrants, who had been intercepted at sea on their way to Europe.
The boat returned to Tripoli with 90 on board was in distress at sea for 2 days, UNHCR said in a statement on Wednesday.
UNHCR and IRC provided medical aid and assistance to all survivors, the statement added.