The rescue ship Ocean Viking with 572 rescued migrants on board is allowed to call at the Sicilian port of Augusta.
The Italian authorities had announced that the rescued were allowed to go ashore, tweeted the organization SOS Méditerranée, which operates the ship, on Thursday evening.
"The relief is enormous that their plight at sea is almost over and the 6 rescues will soon be completed," it said.
The Ocean Viking had rescued the refugees and migrants on six missions in the central Mediterranean since the end of last week.
Several requests for a safe haven allocation had been denied in the past few days.
Of the 572 rescued on board, 183 are minors, according to the organization.
159 of these are children and young people who are not accompanied by an adult.
Two severely physically disabled children and a pregnant woman are also on board.
The Mediterranean is one of the most dangerous escape routes in the world.
According to the IOM, so far this year at least 898 people have died trying to get to Europe this way.
Time and again, private sea rescuers wait days after missions for the Italian or Maltese authorities to assign a safe harbor.