Crystal Palace goalkeeper Wayne Hennessey "did not know" what a Nazi salute was, a Football Association panel has said.

The Wales international was charged after appearing to perform a Nazi gesture in a photograph posted on Instagram by German teammate Max Meyer. Hennessey denied the allegation, and suggested the gesture was "absolutely coincidental" -- and the charge was eventually dropped.

The written reasons for the decision, published on Tuesday, stated the 32-year-old was not punished because he proved he was unaware of the historical significance of the gesture.

"Mr. Hennessey categorically denied that he was giving a Nazi salute," the statement read. "Indeed, from the outset he said that he did not even know what one was.

"Improbable as that may seem to those of us of an older generation, we do not reject that assertion as untrue. In fact, when cross-examined about this, Mr. Hennessey displayed a very considerable -- one might even say lamentable -- degree of ignorance about anything to do with [Adolf] Hitler, fascism and the Nazi regime.

"Regrettable though it may be that anyone should be unaware of so important a part of our own and world history, we do not feel we should therefore find he was not telling the truth about this.

"All we would say [at the risk of sounding patronising] is that Mr. Hennessey would be well advised to familiarise himself with events which continue to have great significance to those who live in a free country."