Ken Riley, aged 86, of Grimesthorpe, chairman of the Normandy Veterans' Association Sheffield branch, said there were inconsistencies in the account of service given by the man - Bob Head - in the BNP's release.
And he said the man's medals - displayed in two rows, one at an angle - were not being worn correctly.
Mr Riley said: "There is no way a Normandy veteran would be voting for the BNP or endorsing them when they fought against fascism. I have suspicions about this person, particularly with the medals not being worn properly."
Mr Riley is currently the face of a campaign being run by Hope Not Hate against the far-right BNP - and said a lot of the quotes in the BNP's publicity drive seem uncannily similar to some of his own.
Paul Meszaros, regional spokesman for Hope Not Hate, said: "It's disgraceful. We know Ken is a real war hero. It would be despicable if they have used our press release as the basis for theirs."
In Hope Not Hate's press release, Mr Riley says: "When I enlisted in the Army 66 years ago, I did it for Britain. Now I need you to do something for me. The BNP is trying to strangle our great nation with the same extremist and fascist agenda that Hitler's Nazis threatened us with decades ago. Hope Not Hate is on the front lines of our fight."
Mr Head begins: "When I enlisted in the Army in 1942, aged 18, I did it for Britain. Now I need you to do something for me. The British National Party is on the front lines of our fight."
Other lines appear in both men's statements, such as "Today, the war isn't being fought on the battlefield but in the ballot box" and "If I had my health I would be out there with them. But I can't - so I'm asking you to volunteer for me".
In the BNP's press release, Mr Head claims to have been part of the 51st Highland Division and says he was involved in the Normandy invasion, the Battle of the Bulge and Operation Market Garden.
But historical records show the 51st Highland Division was not involved in Market Garden - the attempt to take the Rhine bridges at Arnhem.
In a photograph released by the BNP Mr Head is wearing two rows of medals but the top row is at an angle.
Mr Riley said that although the medals on the top row are genuine, they would be worn by any proud veteran in a straight line. And doubts have been expressed about the authenticity of the lower medals, which Mr Riley did not recognise.
The BNP did not respond to requests to The Star's request for comment
The Star
