An organization of state restaurants asked a federal appeals court Tuesday to stop the city from immediately implementing a requirement that some chain restaurants post calories on menus.

The New York State Restaurant Association said in court papers submitted to the 2nd U.S. Circuit Court of Appeals in Manhattan that implementation should be blocked because the case raises legal issues that the courts have yet to address.

The widely expected request came after U.S. District Judge Richard Holwell ruled last week that the city requirement was constitutional and might help the city achieve its goal of reducing obesity.

He held off enforcement of the requirement until Friday so the restaurant association could appeal. Restaurants breaking the rule will not be fined until at least June 6.

In its request for a stay, the restaurant association said in court papers that it planned to press questions of law on appeal that have never before been considered by the courts.

The restaurant association called the regulation an experiment and noted that the city had postponed enforcement of it for many months.

The restaurants argued that the regulation was pre-empted by the federal Nutrition Labeling and Education Act, which gives restaurants discretion and flexibility in whether or how to present nutrition information such as calories.

The restaurants also argued that city government was violating the First Amendment by forcing its view on restaurant patrons — that calories are the only nutritional criterion that diners need to consider.

Kate O'Brien Ahlers, a spokeswoman for the city's legal department, said the city would file a response to the restaurant's papers on Wednesday.