St George, Utah: US polygamist sect leader Warren Jeffs, whose word was considered God's will to his fundamentalist church of breakaway Mormons, has been convicted of being an accomplice to rape by forcing a 14-year-old girl to marry her first cousin.

Jeffs, the self-described "prophet" of the Fundamentalist Church of Jesus Christ of Latter-Day Saints, or FLDS, spent 15 months on the run and was on the FBI's "Most Wanted" list before his arrest in August 2006.

The tall, gaunt Jeffs showed no expression as the verdict was read on Tuesday. The rape victim, who is now 21 and remarried, sat in the front row of the crowded courtroom packed with media and Jeff's supporters.

Sentencing was set for November 20. Jeffs, 51, faces five years to life in prison for each of the two felony charges.

Revered by his faithful and demonised by others, Jeffs has become the face of the FLDS, whose approximately 7,500 members live in a secluded red-rock enclave at the Utah-Arizona border.

FLDS women wear long, pioneer-style dresses and long braided hair, and members distrust outsiders. The trial has riveted Utah, the western state with a majority Mormon population, many of whom consider polygamy a thorny issue.

A part of the early tenets of the Mormon religion, polygamy was rejected in 1890 as Utah sought statehood. The FLDS - the largest organised polygamist group in Utah - is not associated with the Church of Jesus Christ of Latter-day Saints, whose members are called Mormons.

Polygamy, which is illegal in the United States, was not a legal issue in the Jeffs trial. The approximately 37,000 proponents of the practice in Western states are rarely prosecuted due to lack of resources.

Prosecutors claimed during the two-week trial that the religious leader had encouraged forced sex in arranging the wedding despite the girl's objections, and instructing the couple to "go forth and multiply".

The woman, who the court requested not be identified, said that when she later begged to be released from her union, Jeffs told her she should repent and instructed her to give herself "mind, body and soul" to her 19-year-old husband.

Within the community, Jeffs' accuser testified, women are taught to be submissive and "keep sweet", while dissent can lead to exile and religious damnation.

Jeffs often punished men in the community by reassigning their wives and children to other men, she said.