The message, written in pencil and dated 9 September 1944, bears names, camp numbers and home towns of seven young inmates from Poland and France.

At least two survived the Nazi camp, an Auschwitz museum official said.

The bottle was buried in a concrete wall in a school that prisoners had been compelled to reinforce.

The school's buildings, a few hundred metres from the camp, were used as warehouses by the Nazis, who wanted them protected against air raids.