Arizona's immigration law drew more international headlines Wednesday when an electric-utility regulator responded to Los Angeles' boycott efforts by suggesting it stop using power from Arizona.

Read Pierce's letter to Los Angeles mayor on boycott

The response, which Los Angeles considered a threat to its power supply, was picked up by television stations, newspapers, online versions of magazines and a variety of pundits, who painted vivid pictures of a metropolitan city in the dark after having the plug pulled from its power source. Arizona provides about a quarter of the Southern California city's power.

"If an economic boycott is truly what you desire, I will be happy to encourage Arizona utilities to renegotiate your power agreements so Los Angeles no longer receives any power from Arizona-based generation," Arizona Corporation Commissioner Gary Pierce said in a Tuesday letter to Los Angeles Mayor Antonio Villaraigosa.

Pierce, who has no authority to cut off the city's electricity, said that he did not intend his letter as a literal threat but that he wrote it to illustrate the close ties between Los Angeles and Arizona and the trouble that a boycott could cause in both places.

"A boycott is an unfriendly gesture," he said Wednesday. "Where do you expect that to go?"

Los Angeles is among a number of cities and organizations that have called for boycotts of Arizona until the state repeals its new immigration law. The law, which goes into effect July 29, makes it a state crime to be in the country illegally. It states that an officer engaged in a lawful stop, detention or arrest shall, when practicable, ask about a person's legal status when reasonable suspicion exists that the person is in the U.S. illegally.

Pierce, who is running for re-election, said in his letter that if the Los Angeles City Council "lacks the strength of its convictions to turn off the lights in Los Angeles and boycott Arizona power, please reconsider the wisdom of attempting to harm Arizona's economy."

Cutting off power to Los Angeles would be no simple task. Federal regulators oversee the power grid. And there's the matter of California utilities actually owning a share of some of the Arizona plants that provide the state power.

The Los Angeles Department of Water and Power, Southern California Edison and other California utilities have an ownership stake in the Palo Verde Nuclear Generating Station west of Phoenix and in the Navajo Generating Station, a coal plant in northern Arizona.

Because most national media have no knowledge of the power plants' ownership structure, and because Pierce's letter didn't explain it, most media took the letter as a direct threat to black out the city.

"A quarter of America's second-largest city could be plunged into darkness," wrote the Daily Telegraph of London.

Bloggers, critics and experts quickly wondered where such a debate would lead next. Fights over water supplies? Gasoline that Arizona imports from California? Shipping cargo at the Port of Los Angeles?

Villaraigosa and Los Angeles officials took the letter as a threat.

"The mayor stands strongly behind the City Council on this issue and will not respond to threats from a state which has isolated itself from the America that values freedom, liberty and basic civil rights," he said in a prepared statement.

Councilman Ed Reyes, who supported the Arizona boycott, said the letter was "hostile."

Los Angeles Councilman Greig Smith was the only one to oppose the Arizona boycott.

"(Pierce's) letter was wrong, but I understand what I think he's trying to say is that this isn't going to accomplish anything," Smith said. "I congratulate him on his effort."

But he said the letter is unlikely to change any minds in Los Angeles.

Corporation Commission Chairwoman Kris Mayes said that she is frustrated with the LA boycott but that Pierce's letter does not reflect the stance of the commission.

"It would be pretty unfortunate, and equally ridiculous, if California were to counter-threaten to cut off our gas supplies," Mayes said.

Pierce said he hopes the attention causes Los Angeles and other cities boycotting to back off their efforts once they realize the cities' ties to Arizona.

"It's almost like two communities in Arizona deciding to boycott each other," he said. "We're awful close and interrelate so much, I just think it's an impractical solution and not very well thought out (by Los Angeles). Really, guys, let's cool it and move on."