Fourteen crosses commemorating people who died trying to cross the Berlin Wall have been returned, a week after a group said it took them to highlight the plight of refugees trying to enter Europe today.

Police said four people were seen bringing the white crosses back to their site near the German parliament building on Sunday night. Hours earlier, the German capital marked the 25th anniversary of the fall of the wall by releasing thousands of balloons into the sky along the former border.

A police statement Monday said the three men and a woman fixed the crosses back in place "under police supervision." Officers took their personal details then let them go.

A group calling itself the Center for Political Beauty has claimed it was behind the crosses' disappearance.