A federal appeals court appeared willing Monday to reinstate, but weaken, a central provision of an Arizona law allowing police to stop and question suspected illegal immigrants.

A three-judge panel of the Ninth U.S. Circuit Court of Appeals indicated that it would authorize police to demand papers from those they reasonably suspected of being in the country illegally, but would not allow authorities to arrest or prosecute them under state law.

That would still allow suspects to be referred to U.S. authorities for deportation, however.

At an hourlong hearing in a packed San Francisco courtroom, two panel members suggested that a federal judge had gone too far when she blocked enforcement of all major provisions of the law.

Responding to an Obama administration lawsuit that claimed Arizona was interfering with federal regulation of immigration, U.S. District Judge Susan Bolton issued an injunction July 28, less than 24 hours before the law was to take effect.

The judge barred Arizona from requiring police to order anyone they stopped for a crime, and reasonably suspected of being in the country illegally, to produce proof of legal status. She also blocked a provision allowing police to detain anyone they believed was deportable because of a previous conviction.

In addition, Bolton blocked provisions of the law making it a crime for illegal immigrants to seek work, and for a noncitizen to be in the state illegally or to fail to carry immigration documents.