An Australian Jewish soldier who killed a civilian in Afghanistan was allegedly described in letters by a Muslim man as "a dirty animal" and "not much better than" Hitler, a court has heard.

Haron Maris, also known as Sheikh Haron, is appealing an unsuccessful attempt to have his case dismissed in the District Court of New South Wales after he allegedly sent letters to families of soldiers who died in Afghanistan, according to Australian Associated Press.

In a letter about a Jewish soldier, Sheikh Haron allegedly wrote: "Some Jews who blame Hitler for violations of human rights are not much better than him."

He also allegedly described him as "a thousand times worse" than a pig.

In the NSW Court of Criminal Appeal on Tuesday, barrister John Agius read from some of the alleged letters, which were sent to politicians as well as the Jewish community. "A Jewish man who kills innocent Muslims, civilians, is not a pig. He's a thousand times worse. Some people don't eat the meat of pig but they are dirtier than pig.

"What's the point when some people don't eat pork while their behaviour is worse than dirty animals?"

But Sheikh Haron's lawyer, Guy Reynolds, said the comments were not necessarily offensive. A lawyer for Amirah Droudis, who faces charges of aiding and abetting the sendfing of the letters, said that "insults are a legitimate part of the political discourse".

Neither of the men appeared at Tuesday's appeal.