By David Ingram and Aruna Viswanatha

WASHINGTON (Reuters) - The Obama administration sued North Carolina on Monday to block newly enacted voting rules that it says violate federal civil rights law, including a requirement for voters to show photo identification at the polls.

The challenge is the second of its kind in recent months aimed at voting changes in a Republican-led state. In August the Justice Department sued to keep Texas from carrying out a voter identification requirement enacted in 2011.

The department's civil rights enforcers are acting after the U.S. Supreme Court in June invalidated part of the 1965 Voting Rights Act they previously relied on.

"Allowing limits on voting rights that disproportionately exclude minority voters would be inconsistent with our ideals as a nation," said Attorney General Eric Holder, who announced the suit at a news conference in Washington with North Carolina-based Justice Department lawyers.

Republican Governor Pat McCrory signed the state's sweeping voting changes into law in August, saying: "Common practices like boarding an airplane and purchasing Sudafed require photo ID, and we should expect nothing less for the protection of our right to vote."

Civil rights groups sued immediately, and U.S. Senator Kay Hagan, a Democrat, asked Holder to review the law.

Holder said the Justice Department suit asks a federal court in the Middle District of North Carolina to block four provisions of the state law: The elimination of seven days of early voting prior to Election Day; the elimination of same-day voter registration during early voting; the prohibition on counting certain provisional ballots, which a voter fills out when there are questions about his or her registration; and the adoption of an ID requirement that is stricter than the Justice Department allows.

FIGHT ALONG PARTY LINES

Democrats and Republicans fight vigorously over such requirements because they affect voter turnout and may swing close elections. For civil rights advocates, they also echo the earlier, century-long fight to win voting rights for black Americans in the U.S. South.

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Requirements for voters to show identification have been the biggest flashpoint. The Justice Department has approved of them in some states, such as in Virginia, that take steps to ensure IDs are available at little to no cost, but not in states where it said the mandate would be a burden on the poor and minorities. Holder has compared them to poll taxes.

The challenge to North Carolina would fall under the Voting Rights Act's Section 2, which prohibits state voting practices or procedures that discriminate by race.

The Justice Department asked federal court to place North Carolina under a preclearance requirement, in which any voting change would require federal approval before taking effect, said a person briefed on the Justice Department's plan. Much of North Carolina had a preclearance requirement before the Supreme Court's ruling in June.

Holder has called the Supreme Court's ruling deeply flawed, and in a speech on September 20 said the Justice Department "will not allow the court's action to be interpreted as ‘open season' for states to pursue measures that suppress voting rights."

Republicans argue that the measures prevent voter fraud.

(Editing by Howard Goller, Stacey Joyce, Colleen Jenkins and Phil Berlowitz)