AUSTIN, Texas (AP) _ A federal judge ruled that Texas can act as guardian of Alabama-Coushatta Indians, overturning a state attorney general's ruling that some tribe members feared could force them into bankruptcy.

The action by U.S. District Judge James Nowlin came in a lawsuit filed by the tribe after Attorney General Jim Mattox held that the state's guardianship of the Indians violated Texas' 1972 equal rights law.

The ruling has cost the tribe hundreds of thousands of dollars in state subsidies and lost tax exemptions, members say.

The Alabama-Coushattas, who live on a reservation near Livingston, in east Texas, have received state assistance since 1954, when the federal government relinquished its guardianship of about a dozen U.S. tribes.

A 1983 opinion by Mattox said the state could not discriminate either in favor of or against the Alabama-Coushattas ''simply because they are Indian.''

But Nowlin said in Monday's ruling, ''The special benefits accorded the tribe by the state over the years flow from the Indian tribal membership, not their race.''

Austin lawyer Alan Minter said Wednesday that the Alabama-Coushatta, who have received state funds since 1929, feared that such appropriations would be jeopardized as a result of Mattox's opinion.

The tribal land in Polk County includes a 1,280-acre tract bought by the state in 1854-55 as a home for the Alabama-Coushattas, and a 3,071-acre tract purchased by the federal government in 1928.

That land was transferred to the state in 1953, and the next year Congress transferred all trust responsibility for the tribe to the state.

Nowlin said the narrow question before the attorney general three years ago was whether Texas game and fish laws could be enforced on the reservation.

''Unfortunately, the broad, sweeping conclusions of the opinion have fueled a maelstrom of controversy,'' the judge said.

As a result of the opinion, he said, the state comptroller had questioned reservation expenses submitted by the Texas Indian Commission and the director of the Minerals Tax Division had ruled that oil and gas royalties from the 1,280-acre tract are subject to the state severance tax.

Tribal leaders also said the opinion could force the tribe to pay property taxes.

In July 1984, the Indians filed suit to force the state to become a trustee for the Indians.

Nowlin said in his opinion that the issues were whether a trust relationship exists between the tribe and the state, and whether a 1954 federal law ''imposes upon the state a duty to accept and hold title to the state tract.''

In granting the Alabama-Coushattas' motion for summary judgment, without trial, Nowlin said such a trust did exist.