WASHINGTON (AFP) — The founder of Mormonism, which for decades allowed polygamy, had as many as 40 wives including one who was only 14, the US-based church has acknowledged.

Joseph Smith (1805-1844), founded the Church of the Latter-day Saints, Mormonism’s formal name, and is regarded by followers as a prophet.

The Mormon Church said in an online essay last month that Smith is estimated to have had between 30 and 40 wives, some of whom were already married.

The New York Times, which first reported the disclosure Tuesday, said Smith probably did not have sex with all the wives because some were “sealed” to him only for the next life.

The Mormon essay said the oldest of the women “sealed” to Smith was 56, and the youngest was 14.

“Marriage at such an age, inappropriate by today’s standards, was legal in that era, and some women married in their mid-teens,” the Mormon essay states.

According to the essay, “an angel appeared to (Smith) three times between 1834 and 1842 and commanded him to proceed with plural marriage when he hesitated to move forward.”

During the third visit, the angel supposedly threatened to kill Smith with a sword unless Smith obeyed the commandment.

The Times said Smith has long been portrayed by the church as a loyal partner to his first wife, Emma.

An official Mormon website says that today, “the practice of polygamy is strictly prohibited … as it has been for over a century.”

But polygamy was part of the church’s teachings for 50 years during the religion’s early days.

“Much of what you’ll find in the essays on polygamy has been published in diverse sources and known among long-term and well-read members, historians and Church leaders for many years,” Mormon spokesman Eric Hawkins told AFP.

“The Church has now gathered this information into a single location as a convenient means of placing these resources in the hands of all members.”

The Mormon Church has written several essays in recent months addressing contentious topics, including a ban on black people from becoming priests that was only lifted in 1978.

The Mormon Church claims 15 million members worldwide, including six million in the United States.

The faith is also known internationally for its practice of sending young missionaries around the world.

In 1820, a 14-year-old Smith claimed he’d had a vision of God, while living in western New York state. The event went on to be seen as a founding moment in the history of Mormonism.

Facing persecution, Mormons moving westward eventually sought refuge in what is now Utah, making Salt Lake City their “capital.” Followers of the faith are to this day concentrated in this western part of the United States.

Smith was killed by an angry mob while in prison.