PHOENIX — Arizona prison officials need to show a real hardship if they want to deny halal meals to a Muslim inmate, the 9th U.S. Circuit Court of Appeals ruled Wednesday.

In a unanimous ruling, the judges overturned a lower court decision which accepted the claims of the state Department of Corrections that providing the meals to Amin Shakur would create additional costs and administrative burdens. The appellate judges said there was no evidence that the state actually looked into the real cost.

The judges also noted that the state already provides two kinds of kosher meals for Jewish inmates. That, they said, not only raises questions about whether the state is has a reason for its disparate treatment between Jewish and Muslim prisoners but also casts “substantial doubt’’ on the state’s claims that accommodating Shakur and other Muslim inmates would result in significant problems.

Wednesday’s ruling sends the case back to U.S. District Court Judge Paul Rosenblatt, who initially threw out Shakur’s lawsuit.

And that could put the Department of Corrections into an interesting position: A spokesman for the state Department of Corrections said Wednesday there is currently no real difference between the cost of regular and kosher meals. Bill Lamoreaux said both cost an average of $1.28 each.

Court records show Shakur, serving a 21-year term for burglary, kidnapping and theft, changed his religious designation during his incarceration from Catholic to Muslim.

In 2000 he originally asked for a diet of vegetables and milk; the one he gets also includes eggs.

Shakur also said he could have meat if it were slaughtered and prepared in the ritual way to make it halal. He said that kosher meat would be consistent with those requirements and provide an alternate source of protein.

Prison officials rejected the request for a kosher diet, saying there is no evidence that eating halal meet is a requirement of his religion. And they said the vegetarian diet allows him to avoid eating non-halal meat.

That led to the lawsuit.

Appellate Judge Diarmuid O’Scannlain said the fact Shakur admitted there is no requirement he eat halal meat does not end the matter. He said the trial court should also have considered the inmate’s claims that the all-vegetarian diet both denies him protein and causes gastrointestinal distress that interferes with his religious practices.

Beyond that, O’Scannlain said the cost claims are dubious.

Relying only on an affidavit of a pastoral administrator, the state argued that providing kosher meals to all 850 Muslim inmates would run $1.5 million a year; providing them with halal meat would run “millions of dollars annually.’’

“There is no evidence in the record that Arizona Department of Corrections actually looked into providing kosher meat to all Muslim prisoners, which could potentially result in economies of scale that would reduce the overall costs of the meals,’’ the judge wrote. In fact, O’Scannlain said, there is no evidence the state solicited bids or even studied the effect on the budget.

And the judge said there also is no evidence all Muslim inmates would demand kosher meat.

O’Scannlain also said there is evidence that a prison in Washington state a halal meat diet to inmates for what a court said is “minimally more expensive than the standard diet.’’ The said that puts the burden on Arizona prison officials to explain why another institution is able to accommodate those inmate needs.