Arkansas is temporarily blocked from enforcing a law that would have allowed criminal charges against librarians and booksellers for providing “harmful” materials to minors, a federal judge has ruled.

US district judge Timothy L Brooks issued a preliminary injunction against the law, which also would have created a new process to challenge library materials and request that they be relocated to areas not accessible by kids.

The measure, signed by Republican governor Sarah Huckabee Sanders earlier this year, was set to take effect on August 1.

A coalition that included the Central Arkansas Library System (CALS) in Little Rock had challenged the law, saying fear of prosecution under the measure could prompt libraries and booksellers to no longer carry titles that could be challenged.

The judge also rejected a motion by the defendants, which include prosecuting attorneys for the state, seeking to dismiss the case.

The ACLU of Arkansas, which represents some of the plaintiffs, applauded the court’s ruling, saying that the absence of a preliminary injunction would have jeopardised First Amendment rights.

Holly Dickson, the executive director of the ACLU in Arkansas, said in a statement: “The question we had to ask was — do Arkansans still legally have access to reading materials?

“Luckily, the judicial system has once again defended our highly valued liberties.”

The lawsuit comes as politicians in an increasing number of conservative states are pushing for measures making it easier to ban or restrict access to books.

The number of attempts to ban or restrict books across the US last year was the highest in the 20 years the American Library Association has been tracking such efforts.

Laws restricting access to certain materials or making it easier to challenge them have been enacted in several other states, including Iowa, Indiana and Texas.

Arkansas attorney general Tim Griffin said in an email on Saturday that his office would be “reviewing the judge’s opinion and will continue to vigorously defend the law”.

The executive director of CALS, Nate Coulter, said the judge’s 49-page decision recognised the law as censorship, a violation of the Constitution and wrongly maligning librarians.

“As folks in southwest Arkansas say, this order is stout as horseradish!” he said in an email.

“I’m relieved that for now the dark cloud that was hanging over CALS’ librarians has lifted.”

The Arkansas lawsuit names the state’s 28 local prosecutors as defendants, along with Crawford County in west Arkansas.

A separate lawsuit is challenging the Crawford County library’s decision to move children’s books that included LGBTQ+ themes to a separate portion of the library.

The plaintiffs challenging Arkansas’ restrictions also include the Fayetteville and Eureka Springs Carnegie public libraries, the American Booksellers Association and the Association of American Publishers.