A state appellate court has upheld a Santa Barbara judge's order requiring the Boy Scouts of America to turn over two decades of confidential files on alleged sexual abuse.

The Boy Scouts will appeal the decision to the California Supreme Court, a spokesman said Thursday.

Lawyers for a former Scout, who was 13 when a volunteer leader sexually abused him in 2007, contend that the files will expose a "culture of hidden sexual abuse" in Scouting and the organization's failure to warn boys and their parents.

The lawsuit alleges that a local Scout official tried to keep the boy's mother from reporting the crime to police, saying that it was an example of efforts to conceal abuse in Scouting. The youth group denies the allegations.

In January, Santa Barbara County Superior Court Judge Donna Geck ordered all files dating to 1991 turned over to the boy's lawyers but not made public.

In April, the Scouts filed a writ with the California 2nd District Court of Appeal, seeking to reverse Geck's order. The group contends that the records must remain confidential to protect the privacy of victims, those who report abuse, and those wrongly accused.

"The BSA believes confidentiality of the files helps to encourage prompt reporting," spokesman Deron Smith said. "The files are only one component of BSA's established Youth Protection program."

In October, more than 1,200 of the confidential files from 1965 to 1985 were made public by order of the Oregon Supreme Court, a decision that did not have a direct bearing on the California case.

Timothy Hale, the family's lawyer in the Santa Barbara case, blasted the Scouts' efforts to keep more recent files under wraps. By shielding the identities of "thousands of perpetrators who are roaming free in society," he said, the Scouts are putting children at risk.

"If their first priority is child welfare, then stop the secrecy game," Hale said.

kim.christensen@latimes.com