Monday, May 8, 2006 Posted: 0043 GMT (0843 HKT)
Jeffs, 50, is accused of arranging marriages between underage girls and older men.
He is wanted in Arizona on criminal charges of sexual conduct with a minor. He also was charged in Utah with rape as an accomplice.
"We are doing everything we can to track him down," Fuhrman, special agent in charge of the FBI's Salt Lake City field office, said Saturday.
Jeffs is the leader of the polygamous Fundamentalist Church of Jesus Christ of Latter Day Saints, based in the neighboring communities of Hildale, Utah, and Colorado City, Arizona.
The sect split from mainstream Mormonism after the broader church renounced polygamy in 1890. The mainstream Latter Day Saints church excommunicates members found to be practicing polygamy.
Jeffs has not been seen by anyone outside of the Fundamentalist Church of Jesus Christ of Latter Day Saints community for nearly two years. He also faces a charge of unlawful flight to avoid prosecution.
By putting him on the Top 10 list, the FBI's reward increases from $50,000 to $100,000. The list is also distributed worldwide.
"We think that the inclusion of a $100,000 reward is going to mean that people are going to be much more aware of Warren Jeffs, they're going to be much more aware of what he looks like, and they're going to be much more willing to come forward to assist us in our efforts to locate him," U.S. Attorney Paul Charlton said at a news conference in Phoenix.
The FBI's announcement coincided with Jeffs' case appearing on the television program "America's Most Wanted."