UPDATE 1-U.S. spy agencies warn of growing domestic terrorism threat

Adds details from spy agencies' report

By Mark Hosenball

WASHINGTON, March 17 (Reuters) - U.S. spy agencies said on Wednesday that racially motivated extremists and militia extremists present the most lethal domestic terrorism threats, and warned that the threats could grow this year.

The assessment issued by the Office of the Director of National Intelligence said racially motivated extremists were most likely to conduct major attacks against civilians, while militia members typically target police and government personnel and buildings.

The agencies who contributed to the report, including the FBI, the Department of Homeland Security and the National Counterterrorism Center, said that domestic extremists who promote white racial superiority have potentially troubling contacts with foreign extremists and that a small number of American extremists have traveled abroad to network with overseas counterparts.

The agencies said that other domestic extremist categories which concern government investigators include animal rights and environmental activists, anti-abortion protesters, anarchists and people who call themselves sovereign citizens who "believe they are immune from government authority and laws."

(Reporting by Mark Hosenball; Editing by Tim Ahmann and Jonathan Oatis)

((tim.ahmann@thomsonreuters.com; +1 202 898-8370; Reuters Messaging: tim.ahmann.reuters.com@reuters.net))