The military said in a statement it responded early Saturday to a sinking boat with at least 39 Syrian nationals on board "who were heading to Cyprus via an illegal route".

"A navy patrol unit immediately headed there, retrieved the body of a five-year-old child and rescued the rest" of the passengers, it said.

Four of those rescued were taken to nearby hospitals with the help of the Lebanese Red Cross, the statement added.

The Red Cross confirmed to AFP that it was involved in the rescues, but declined to give any further details.

A security source told AFP that Palestinian refugees were also among those rescued.

"The child who died was a Palestinian refugee from the Nahr al-Bared camp," in the northern Lebanese city of Tripoli, the source said.

The four people being treated in hospital included one Palestinian woman and three Syrians, the source added.

The United Nations' refugee agency (UNHCR) has registered nearly one million Syrian refugees in Lebanon.

Humanitarian representatives and government officials say the number is likely much higher, since many refugees who have fled Syria's civil war to Lebanon are not officially registered with the United Nations.

Tens of thousands of Palestinian refugees also live in Lebanon, in a dozen squalid camps spread across the country.

Earlier this month, Cyprus announced it was looking to broker a repatriation agreement with Beirut because of an increased influx of migrants from Lebanon to the Mediterranean island.

Interior Minister Constantinos Petrides said his country faces one of the largest migratory flows per capita, with 4,022 asylum requests in the first eight months of 2018 -- 55 percent more than in the same period last year.