By Justin Madden

(Reuters) - A federal judge on Thursday blocked an Indiana law prohibiting abortions based on genetic abnormalities, according to court documents.

U.S. District Court Judge Tanya Walton Pratt granted a preliminary injunction sought by Planned Parenthood of Indiana and Kentucky, which argued that the new state law was unconstitutional and violated women's rights. The law was due to go into effect on Friday.

The American Civil Liberties Union sued the state on behalf of Planned Parenthood.

"The United States Supreme Court has stated in categorical terms that a state may not prohibit any woman from making the ultimate decision to terminate her pregnancy before viability," Pratt said in the court documents, which were reviewed by Reuters.

The office of Indiana Attorney General Greg Zoeller said in a statement on Thursday that state lawyers would review Pratt's ruling and decide if they would appeal the decision.

Indiana Governor Mike Pence signed the bill into law in March, but Planned Parenthood sued the following month to block it. The law made Indiana the second U.S. state following North Dakota to prohibit abortions based on a prenatal diagnosis of disabilities such as Down syndrome.

“While disappointed in today's ruling, Governor Pence remains steadfast in his support for the unborn, especially those with disabilities," Kara Brooks, a spokeswoman for Pence, said in an emailed statement. "The governor will continue to stand for the sanctity of human life in all stages."

State officials had argued in court that the law did not violate the U.S. Constitution.

The lawsuit named the Indiana State Department of Health, prosecutors of several counties and the state medical licensing board.

"We are extremely pleased that Indiana's attempt to violate women's basic rights has been thwarted," Ken Falk, legal director of the American Civil Liberties Union of Indiana, said in a statement.

"This law attempted to do exactly what Supreme Court precedent said could not be done: invade a woman's privacy rights by preventing her from deciding whether to obtain a pre-viability abortion," he said.

Planned Parenthood does not ask patients to disclose why they are obtaining an abortion, but under the new law doctors would have been mandated to report if a fetal anomaly was present before the abortion.

(Reporting by Justin Madden in Chicago)