Homeland Security Secretary Janet Napolitano admitted Monday that she has not read the controversial Arizona immigration law even though she's gone on television to criticize it, and continued to assert that it was "bad law enforcement law."

The admission comes after Attorney General Eric Holder, who earlier warned the law could create a "slippery slope" toward racial profiling, told a House committee last week that he had not read the bill either. On Tuesday, State Department spokesman P.J. Crowley said he too had not read the bill, even as he defended diplomatic official Michael Posner for comparing the law to Chinese human rights violations.

Napolitano discussed the policy under questioning by Sen. John McCain, R-Ariz., during a Senate Homeland Security Committee hearing on the BP oil spill response.

"I have not reviewed it in detail. I certainly know of it," the former Arizona governor said when asked by McCain whether she had a chance to give the language a close look.

Nevertheless, Napolitano said, "That's not the kind of law I would have signed." Napolitano explained that she dealt with "laws of that ilk" in Arizona before and that most law enforcement groups were opposed to them.

"It's a bad law enforcement law," she said. "I believe it mandates and requires local law enforcement or puts them into a position many do not want to be placed in."

But McCain pressed Napolitano to provide more information later on about "what specific aspect of the law" would hurt law enforcement, "since the majority of law enforcement in Arizona strongly supports this legislation."

Arizona Gov. Jan Brewer, a Republican, signed the immigration legislation last month -- Brewer, who was formerly Arizona's secretary of state, succeeded Napolitano when she left for Washington.

The Arizona policy requires local law enforcement to verify the residency status of anyone they suspect of being an illegal immigrant and empowers them to turn anyone who doesn't check out over to federal custody.

The law prohibits officers from solely considering race or nationality in implementing the law, though critics say the law will lead to racial profiling.

That was a concern expressed by Holder two Sundays ago on ABC's "This Week." After he admitted to the House Judiciary Committee Thursday that he's only "glanced" at the law, Holder said he plans to read it before determining whether it's constitutional.

Napolitano last month told ABC News that the law was "misguided," echoing comments made by President Obama.