(Reuters) - Alaska's Supreme Court has ruled a Native American girl should stay with her adoptive non-Native family instead of tribal relatives, angering a tiny coastal community and dealing another blow to a 36-year-old law governing out-of-tribe adoptions.

The state's top court, in a split ruling it said hinged on the U.S. Supreme Court's 2013 decision in the "Baby Veronica" custody battle, upheld a lower court order that an Anchorage couple be allowed to adopt the girl from the remote western village of Tununak.

The Alaska case, and the "Baby Veronica" decision that led to the return of a 4-year-old Oklahoma girl with Cherokee heritage back to her adoptive parents last year, highlight the clash between Native Americans trying to stop children from being adopted outside their tribes.

Both cases center on the 1978 Indian Child Welfare Act (ICWA), which established a preference for keeping Native American children with their families or tribe to preserve their culture.

In the Alaska case, child protection authorities took custody of the girl in 2008 when she was four months old from a mother the agency said grappled with drug abuse and mental health problems, the state's Supreme Court's Sept. 12 opinion said. In 2009, she was placed with non-Native foster parents.

An Anchorage Superior Court terminated the mother's parental rights in 2011, citing drug problems, making the girl eligible for adoption, the Supreme Court said. In 2012, the court granted the couple's adoption petition when the girl, given the pseudonym Dawn to protect her privacy, was almost 4. The tribe appealed.

"It's a really devastating decision for Native families and children who are going to have their ties severed from their extended families and culture," said Nikole Nelson, director of Alaska Legal Services, which represented the tribe.

The Alaska Supreme Court said there was no alternative party eligible for preferred placement under ICWA because the girl's grandmother, named only as Elise F., did not formally seek to adopt Dawn in Superior Court.

Nelson said forcing impoverished, off-the-grid tribal members to file complicated adoption petitions can be an "insurmountable challenge".

The Superior Court found Elise had little contact with Dawn and that her home was unsuitable because she had an adult son with a criminal record and unsecured firearms and medication inside, among other problems.

The adoptive family could not immediately be reached for comment.

(Editing by Cynthia Johnston and Sandra Maler)