The Obama administration’s legal campaign against restrictive state immigration laws has led to a bitter standoff in Alabama, where Justice Department attorneys are investigating possible civil rights violations.

The federal government already has sued Alabama over its new law, one of three such lawsuits against states that have cracked down on illegal immigration. Now, the Justice Department has opened a civil rights investigation to monitor potential discrimination as parts of the Alabama law take effect.

The standoff has been over Justice’s request for detailed enrollment data from Alabama schools, part of the probe into complaints that the law has prompted Hispanic families to pull their children from school. But Alabama’s attorney general balked and, in a series of blunt replies, questioned the federal government’s authority to demand the information. The state education department had advised school districts not to comply, but this week expressed a willingness to cooperate.

The disagreement , which could lead to a second Justice Department lawsuit, comes after the administration last year sued Arizona and, two weeks ago, filed suit against South Carolina. Government lawyers are also considering challenges to laws in Utah, Georgia and Indiana.

The lawsuits have emerged as a key part of the administration’s efforts on immigration and could serve as a counterpoint to growing criticism in the Hispanic activist community over President Obama’s stepped-up deportation program.

The Alabama law is considered the toughest of six new state immigration statutes, which include provisions giving police new authority to question legal status, among other things.

The dispute has stirred memories of Alabama’s segregationist past, with accusations that the law targets Hispanics. A civil rights group compared Alabama Attorney General Luther Strange to then-Gov. George C. Wallace (D) in 1963 as he resisted federal efforts to enroll black students at the University of Alabama.

“The intemperate language of [Strange’s] letter does remind us of George Wallace in the schoolhouse door,” said Richard Cohen, president of the Southern Poverty Law Center, which set up a hotline to monitor discrimination complaints over the immigration law. He said the hotline has received nearly 4,000 calls.

Strange, a Republican elected last year, vehemently rejected the Wallace comparison and said he would not tolerate discrimination. Supporters of the law defended the attorney general and said concerns about racial profiling of Hispanics are overstated.

“That’s a poisonous thing to say,” said Strange, who defeated Wallace’s son, George Wallace Jr., in a 2006 primary for lieutenant governor.

Legal experts say the level of federal intervention over the immigration laws is extraordinary, particularly since the American Civil Liberties Union and other groups have obtained rulings temporarily blocking all or key parts of the Utah, Georgia and Indiana measures. Federal courts also have blocked the most contested provisions of Arizona’s law.

The Alabama law passed in June after last year’s Republican sweep of the legislature. A federal appeals court last month temporarily blocked the most contested provision, which requires public schools to determine citizenship by seeking children’s birth certificates.

But the U.S. Court of Appeals for the 11th Circuit allowed other parts to take effect, pending a more detailed review of the Justice Department’s appeal. Those include provisions requiring police to check immigration status if they stop someone while enforcing other laws and barring undocumented immigrants from entering into business transactions with the state or being party to a contract.

Civil rights groups say this has led to illegal immigrants being evicted from their homes, not getting paid for work and being unable to purchase some utilities. One victim of domestic violence complained that she wasn’t allowed to seek a protective order from a judge, who threatened to turn her in to authorities, according to the Southern Poverty Law Center.

“The law has had a chilling effect,” said Isabel Rubio, executive director of the Hispanic Interest Coalition of Alabama, who said some Hispanic families have left the state and others are signing custody of their children over to neighbors in case they are deported.

Thomas E. Perez, the Justice Department’s assistant attorney general for civil rights, said federal lawyers are investigating similar complaints, along with reports of racial profiling during traffic stops, Hispanic children being withdrawn from school and bullying of children who show up.

“There’s a real fear in these households,” he said in an interview.

Strange said his office had not heard of such complaints. And Kris Kobach, a senior Justice Department official in the George W. Bush administration who helped draft the Alabama law and is helping coordinate the state’s legal strategy, said the law prohibits consideration of race.

He dismissed reports of discrimination in Alabama as “ridiculous.”

On Nov. 1, Perez wrote to 39 Alabama school districts with significant Hispanic populations, seeking detailed data on student enrollment and absences and giving a Nov. 14 deadline. But Strange replied that Perez had not stated his legal authority to demand the information.

Perez cited a raft of civil rights and other federal laws; Strange replied that Justice had still asserted “no legal authority’” to obtain the data.

Alabama’s interim education superintendent, Larry E. Craven, advised noncompliance in a Nov. 2 letter to school districts. This week, in a letter to Perez, he offered to help districts respond but denied any discrimination in schools.

Perez said the government will take “appropriate action” if it finds violations of civil rights laws.

Several Alabama school districts, citing the state education department’s initial recommendation, said they would not comply with Perez’s request.

“Why should we do it if we’ve been told not to?” said Nancy Pierce, spokeswoman for Mobile County schools, who said pulling the data would be “extremely labor-intensive.”