The release of about 300 illegal immigrants from federal custody in Arizona this week has raised a firestorm of controversy in this volatile border state, which has one of the nation’s toughest laws against illegal immigration and is home to highly vocal groups on both sides of the debate.

Senior Republican officials in the state, including Gov. Jan Brewer and Sen. John McCain, sharply criticized the releases, which the Obama administration said it is carrying out in several states in anticipation of budget cuts under sequestration. Brewer, an outspoken opponent of illegal immigration, called the move “pure political posturing” that would endanger public safety.

McCain, a moderate who has been working with Senate colleagues on a plan for comprehensive immigration reform, said he was “very concerned” about the releases because they are an early indicator of what could happen if sequestration goes into effect Friday. “These people should not be released,” he said. “There’s a reason why they were incarcerated.”

Paul Babeau, sheriff of Pinal County, called the releases a “mass budget pardon” that would put criminals on the streets. “These are aliens with felony convictions, who have been released into my county,” he said in an interview. Babeau said about 50 illegal immigrants had been freed by U.S. Immigration and Customs Enforcement from the Pinal County jail, which he oversees, “without warning and under cloak of secrecy. It’s outrageous.”

Several human rights organizations and legal aid groups here said the freed immigrants posed no threat to the public, had not committed serious offenses and should have been freed long ago rather than being kept in custody at government expense. They described some of the immigrants as innocent victims of Arizona’s strict law, in which local police are required in many cases to turn over suspected illegal immigrants to federal officials.

“These people should have been released a long time ago,” said Sarah Lanius, a spokeswoman for No More Deaths, a non-profit group in Tucson that runs free legal clinics for illegal immigrants. “Every person who comes to our clinic is out on bond from detention and following through on their removal proceedings,” she said. “They were stopped in silly traffic cases or other situations, and they have no business being put through all this. It is a direct contradiction of what the administration promised.”

Lindsay Marshall, executive director of a group called the Florence Immigrant and Refugee Rights Project, echoed this opinion. She said her staff members regularly meet and counsel detainees at all four of Arizona’s detention facilities and that many have no need to be in custody. About 2,300 immigrants are still in custody across the state after this week’s releases.

“There are a lot of people in detention who simply don’t need to be there,” Marshall said. She declined to identify anyone who had been released, but she said many were people who had minor criminal convictions, if any, as well as strong family ties in the United States. “There are alternatives to incarceration that are both less punitive and expensive,” she said. “These are mostly people ICE categorizes as low level, and we definitely think this should be a lot wider.”

An ICE spokeswoman in Phoenix said in a statement that the releases were carried out because of “fiscal uncertainty” over budget cuts and possible sequestration. She said all those released would still be processed for deportation and will “not be let off the hook,” but that “priority for detention remains on serious criminal offenders who pose a significant threat to public safety.”

Homeland Security Secretary Janet Napolitano said this week that her department faced a potential budget cut of $4 billion. She said the government currently has about 32,800 beds for illegal immigrants in detention, at an average cost of $164 per day. In addition to Arizona, the government released incarcerated illegal immigrants this week in California, New Jersey, New York and Texas.

Some law enforcement officials here said they could see both sides of the issue and complained that political grandstanding had made it nearly impossible for officials and experts in Arizona to find a reasonable compromise on how to handle illegal immigrants.

“I hope those they have released were only involved in border-crossing. It they were involved in other criminal acts, that would concern me much more,” Tucson Police Chief Roberto Villasenor said in an interview. But he added that such issues had been hijacked by rhetorical extremism. “No matter what you do, people on both sides scream that it’s all political,” he said. “You don’t know what to believe, and it makes it hard to solve the problem.”