PORTLAND, Ore. -- An Oregon county commission has ordered an incinerator to stop accepting boxed medical waste to generate electricity after learning the waste it's been burning may include tissue from aborted fetuses from British Columbia.

Sam Brentano, chairman of the Marion County board of commissioners, said late Wednesday the board is taking immediate action to prohibit human tissue from future deliveries at the plant that has been turning waste into energy since 1987.

"We provide an important service to the people of this state and it would be a travesty if this program is jeopardized due to this finding," he said in a statement. "We thought our ordinance excluded this type of material at the waste-to-energy facility. We will take immediate action to ensure a process is developed to prohibit human tissue from future deliveries."

Kristy Anderson, a British Columbia Health Ministry spokeswoman, told The Associated Press that regional health authorities there have a contract with a company that sends biomedical waste, such as fetal tissue, cancerous tissue and amputated limbs, to Oregon, where it's incinerated in the waste-energy plant.

The B.C. Catholic, a Vancouver-based newspaper, identified the plant as Covanta Marion, based in Brooks, Ore. When contacted by The AP on Wednesday, a Covanta Marion representative said he did not know if fetal tissue was included in shipments from Canada or elsewhere.

The facility is owned and operated by Covanta in a partnership with Marion County. According to its website, it processes about 500 tonnes per day of municipal solid waste, generating up to 13 megawatts of energy sold to Portland General Electric.

Marion County estimates that the facility processes 635 tonnes of in-county medical waste each year and about 1,100 tonnes from elsewhere, making it a small percentage of the total waste burned. Out-of-town medical waste is charged a higher fee.

County spokeswoman Jolene Kelley said medical waste has been included in the program for some time, but the commissioners never had any indication that fetal tissue might be included.

"We learned that today," she said.

Commissioners did not say why they believe medical waste shipped to the plant should be free of fetal tissue.

Since they have no idea what's been arriving in the sealed shipments, the commissioners decided to temporarily suspend all medical waste, Kelley said. They've scheduled an emergency hearing for Thursday and might rewrite an ordinance to clarify what type of material can be accepted.

Covanta Marion is believed to be the only plant generating energy from waste in Oregon.

The Environmental Protection Agency says medical waste from hospitals is generally excluded from the municipal solid waste used to generate electricity.