May 25 (UPI) -- Federal officials are considering removing undocumented immigrants in California custody as an attempt to undermine the state's sanctuary law.

"Operation Guardian Angel" is intended to "neutralize" sanctuary state rules, U.S. Atty. Bill Essaylie, the top federal prosecutor in Los Angeles explained.

The program employs federal resources at county jails and state prisons -- the places where federal officials say the sanctuary law impedes the work of immigration agents to take custody.

"These laws effectively render federal immigration detainers meaningless," Essaylie said. "While California may be presently disregarding detainers, it cannot ignore federal arrest warrants."

An immigration detainer allows local law enforcement agencies to detain people for up to 48 hours beyond their scheduled release to allow for a transfer to federal custody.