A US federal appeals court has struck down a North Carolina law that requires voters to show photo identification when casting ballots.

The voting restrictions were imposed in the state in 2013, but a court ruled today that the law intentionally discriminated against African-American residents.

The decision also restores a week of early voting, allows residents to register and vote on the same day, and allows voters to cast ballots outside their assigned precinct.

In its ruling, a three-judge panel at the US Appeals Court for the Fourth Circuit said the state legislature targeted African-Americans "with almost surgical precision."

The judges said: "They constitute inapt remedies for the problems assertedly justifying them and, in fact, impose cures for problems that did not exist."

Those in favour of the law had said that it was necessary to combat voter fraud and that shortening the window for early voting would save the state money.

However, critics argued that there is little documented evidence of such fraud and they represented an effort to suppress the minority vote and the youth vote.

The decision came a week after a similar ruling against Texas' voter ID law.

Both cases can be appealed to the Supreme Court, but the justices would not have time to consider them before the November elections.