BISMARCK, N.D. (AP) — Tribes representing tens of thousands of indigenous people on both sides of the U.S.-Canada border are signing a declaration against the planned Keystone XL pipeline.

Leaders of the Blackfoot Confederacy in Canada and the Great Sioux Nation and Ponca tribe in the U.S. plan a Wednesday ceremony in Calgary, Alberta, where pipeline developer TransCanada is based.

Ponca Councilwoman Casey Camp-Horinek says the document will highlight treaty rights and opposition to the proposed $8 billion pipeline to move Canadian crude through the U.S. central Plains. The event also could be a precursor to on-the-ground protests along the pipeline route.

Tribes fear environmental harm. TransCanada maintains the pipeline will be safe, create jobs and boost the economy. Spokeswoman Jacquelynn Benson says the company welcomes the views of indigenous communities.