London: The number of children crossing the Mediterranean Sea has risen by more than two-thirds compared to last year, Save the Children said on Wednesday as it announced the launch of its own search-and-rescue ship.

More than 3,160 people have drowned trying to cross the Mediterranean to Europe this year compared to 2,656 for the first eight months of 2015, according to the International Organisation for Migration.

Most have died on the route between North Africa and Italy.

Save the Children said its rescue service would begin in September and the ship would be able to accommodate about 300 people at a time.

The charity will liaise with the Italian coastguard, which coordinates search-and-rescue operations in the area.

“Children are children, first and foremost. Whatever they are fleeing from, they have the right to be safe,” said Save the Children International CEO Helle Thorning-Schmidt.

“ ... we must stop children drowning ... The Mediterranean Sea cannot continue to be a mass unmarked grave for children,” she said in a statement.

Save the Children said 90 per cent of children landing in Italy in 2016 did not have parents with them.

It did not give any estimates for the number of children who have died in the Mediterranean.

The ship, operating out of Catania, will be equipped with two inflatable rescue boats.

Specialists on board the main vessel will provide rescued refugees with food, water and medical help before taking them to Italy.

Italy remains on the front line of an asylum-seeker crisis now in its third year, with more than 400,000 people arriving by boat since the beginning of 2014.