New claims of sexual abuse at the hands of Roman Catholic clergy are coming from the Blackfeet Indian reservation, bringing the total number of plaintiffs in two lawsuits seeking damages from the diocese that oversees western Montana to at least 280.

One lawsuit alone has 200 plaintiffs after eight more were added Monday. Many are Native Americans who claim they were abused as children at schools, in orphanages, in church or in their homes.

They say the Roman Catholic Diocese of Helena knew or should have known about the abuse, but covered it up instead of stopping it.

The lawsuit said 26 clergy members were involved in the abuse that stretches back to the 1940s.

Plaintiffs' attorney Tim Kosnoff said more alleged victims may emerge from Blackfeet tribal members as he and his associates meet with people on the remote northwestern Montana reservation.

"I think we've just hit the tip of the iceberg up in that community," he said.

Kosnoff and the diocese are pursuing a settlement, and both sides are now interviewing the alleged victims before they meet with a mediator in November.

Kosnoff said about 140 people have been interviewed so far, but he acknowledged the November timeline could be pushed back if more alleged victims are added to the growing list of plaintiffs.

Diocese spokeswoman Renee St. Martin Wizeman said Monday that adding more plaintiffs does not change Bishop George Leo Thomas' resolve to settle the matter.

"This is part of the negotiated resolution that we are pursuing with the plaintiffs' attorneys," Wizeman said.

"Bishop Thomas has a great interest in providing pastoral care to victims, and he is encouraging victims to come forward."

St. Martin Wizeman said the Helena diocese also is seeking mediation in a second lawsuit filed against it by at least 80 Native American plaintiffs making similar claims.

Kosnoff represents alleged sex-abuse victims in a separate lawsuit filed against the Roman Catholic Diocese of Great Falls-Billings, which covers the eastern part of Montana.

He also was a plaintiffs' attorney in the case against the Oregon Province of the Society of Jesus, which in 2011 agreed to pay US$166 million to drop a lawsuit alleging sex abuse in Catholic-run schools across the Northwest and Alaska.

- AP