Francis also waded into a political debate in Europe, calling on the international community to find concrete ways to manage the "migratory flows" in the Mediterranean.

The boat had set off from Zuwara, on Libya's northwest coast, carrying migrants from Egypt, Sudan, Eritrea and Bangladesh, the humanitarian organization said.

In its latest report, the group also said that rival authorities in eastern Libya forcibly expelled several thousand migrants ``without due process or the opportunity to challenge their deportation.''

Those numbers still may be an undercount, though, as testing in war-torn nations like Libya and Yemen remains extremely limited.

Oil-rich Libya was plunged into disorder when a NATO-backed uprising in 2011 toppled longtime dictator Moammar Gadhafi, who was later killed.

"Libya is witnessing a dramatic turn of events that underlines the urgent need to return to a full and inclusive political process," the U.N. support mission in Libya said.

Most of the children are African and between 12 and 15 years old, and some are infants, said the International Rescue Committee. Over 50 of the children have disabilities or are children at risk because their caregivers are sick, it said.

The report comes as the conflict in oil-rich Libya has escalated into a regional proxy war fueled by foreign powers pouring weapons and mercenaries into the country.

Safa Mselhi, a spokesperson for the International Organization for Migration, said the migrants were mostly from Sudan and Eritrea, and included one woman.

Powerful tribes in eastern Libya loyal to Khalifa Hifter closed export terminals and choked off major pipelines at the start of the year.