Some 289 children are known to have died in the first half of 2023 while trying to cross the Mediterranean Sea to Europe, the United Nations said Friday.

The figure is double that recorded in the first six months of 2022, the UN children's agency UNICEF said, as it called for expanded safe, legal and accessible pathways for children to seek protection in Europe.

Verena Knaus, UNICEF's global lead on migration and displacement, said the true figures were likely to be higher as many shipwrecks on the central Mediterranean leave no survivors or go unrecorded.

"The number of children who have lost their lives while attempting to cross the Mediterranean Sea to reach Europe has doubled in the first half of this year compared to the same period last year," she said.

"In the first six months of this year, we estimate 11,600 children made the crossing -- again, nearly twice as many as in the same period in 2022."

UNICEF said that in the first three months of 2023, around 3,300 children -- 71 percent of all children arriving in Europe on the central Mediterranean route -- were recorded as unaccompanied or separated.

The figure is three times higher than in the same period last year.

"These children need to know they are not alone. World leaders must urgently act to demonstrate the undeniable worth of children's lives, moving beyond condolences to resolute pursuit of effective solutions," said Knaus.