The Justice Department on Friday told Alabama's attorney general that it has the "express authority" to investigate potential federal civil rights violations in Alabama's public schools authorized by the state's controversial new immigration law.

Assistant US Attorney General Thomas Perez informed Alabama Attorney General Luther Strange of the federal government's powers two days after Strange requested that the Justice Department cite what legal authority it had to collect enrollment data on Hispanic students in his state's public schools.

"The Civil Rights Division of the Justice Department is tasked with investigating potential violations of civil rights laws that protect educational opportunities for schoolchildren," Perez wrote in a letter. "We know that the longstanding legal tradition in this country of ensuring the right to attend school without being subject to discrimination on any impermissible ground is as critically important to you, as the Attorney General of the State of Alabama, as it is to the Civil Rights Division."

The Justice Department initially requested the enrollment information at Alabama public schools Monday after receiving complaints that the state's immigration law may violate federal anti-discrimination statutes related to education.

But Luther advised the state's school superintendent to decline to handover the data because of the ongoing litigation over the immigration law.

The Justice Department sued Alabama over the statute last summer, arguing the law unconstitutionally invades the federal government's exclusive authority over immigration.

A US district court judge upheld much of the law on Sept. 28, but the 11th Circuit US Court of Appeals on Oct. 14th issued a temporary injunction on several sections of the law pending the outcome of an appeal. The provision that requires school authorities to check the immigration status of all students in Alabama public schools was one of the sections the 11th Circuit blocked.

In their investigation, the Justice Department on Monday asked Alabama public schools for a list of all enrolled students as of Sept. 27, a list of all students who have withdrawn from school since the academic year started plus the reason for the exit, and a list of all students who have had at least one unexplained absence since Sept. 27.

The federal government has asked the schools to include students' races, nations of origin and English Language Learner statuses in their lists.

The Justice Department says that enforcement of Alabama's immigration law in public schools may violate the Civil Rights Act of 1964 and the Equal Educational Opportunities Act.