A team from the International Committee of the Red Cross (ICRC) has been released after being detained by police in the Ukrainian town of Manhush - which is now reportedly in Russian hands.
The ICRC said this was a "great relief". The team had been trying for several days to reach the besieged city of Mariupol, to deliver aid and evacuate those who wish to leave.
For now, it is reported that the team has returned to Zaporizhzhia. It remains unclear if or when they will continue the mission to Mariupol.
The aid organisation said: "The team is focused now on continuing the humanitarian evacuation operation.
"This incident yesterday shows how volatile and complex the operation to facilitate safe passage around Mariupol has been for our team, who have been trying to reach the city since Friday."
