A CONFESSION etched on a newly discovered lead sheet has shaken the Mormon Church by linking its revered leader, Brigham Young, with one of the worst massacres in American history.

The note claims that the founder of Salt Lake City ordered the 1857 Mountain Meadows Massacre, when a wagon train of 120 settlers, mostly women and children, were killed after they had thrown down their weapons on a promise of safe passage.

The Church of the Latter-Day Saints, as Mormons are properly known, first tried to blame Indians for the slaughter but after huge pressure from the federal government, John D Lee, a militiaman who was Young's adopted son, was tried and executed 20 years later for organizing the attack.

The Church has always maintained that the militia acted alone, despite persistent claims that documents incriminating its leaders were burned at the end of the 19th century. Schoolbooks in Utah do not mention the incident and it has been airbrushed out of the religion's official history.

The lead sheet is the first evidence to directly link the killings to Young, who is considered a modern-day prophet by Mormons after he led them on their trek across America to found the city at Salt Lake.

It was found during restoration work on the debris of Lee's Fort, the citadel at which Lee's militia forces were based on the Colorado River, under several inches of dirt and rat droppings in the main chamber.

It is signed by Lee, who had 19 wives and 64 children, and claims to be written "by my own hand", 15 years after the events it describes.

Filled with misspellings, grammatical errors and halted sentences, it says: "I do not fear athorty for the time is closing and am willing to take the blame for Fancher."

The wagon convoy was known as the Fancher party, after Alexander Fancher, who led it.

It continues: "Col Dane, Maj Higby and me - on orders from Pres Young thro Geo Smith took part - I trust in God - I have no fear - Death hold no terror."

The massacre occurred amid a climate of war hysteria as Utah's Mormons prepared for an invasion by federal troops, who had been dispatched to suppress the theocracy established in the region a decade earlier.

As the settlers' convoy entered the state en route from Arkansas to California, rumours spread that it contained men who had killed a Mormon leader and church leaders vowed vengeance.

After a five-day siege the Mormon militia sent in a party under a flag of truce and promised safe passage. When the "gentiles" left their encampment all but the youngest children were killed.

Historians were yesterday clamoring to examine the sheet, and tests were being conducted to determine where the lead was mined in an attempt to date it.

The possibilities of a forgery or a false claim by Lee have not been ruled out, but experts said that at the time that it was not unusual for people who wanted to preserve a record to etch it on lead.

Scott Fancher, a lawyer in Harrison, Arkansas, who is president of the Mountain Meadows Monument Foundation and a descendant of Alexander Fancher, welcomed the discovery as a significant step in forcing the Church to face up to the reality of its past behaviour. He said he had long believed that Young sanctioned the massacre as a demonstration to federal authorities that only he could control the Paiute Indians who supposedly took part in the attack.

"The only thing that surprises me is that it's taken this long to find the letter, not the admission of guilt or that Lee pointed the blame at Young," he said.

In Salt Lake City, Mormon leaders insisted that further checks had to be conducted on the authenticity of the note before it could be accepted as a historical document.

Dale Bills, a Mormon spokesman, insisted that Young did not order the killings although "some members of the faith acted independently at Mountain Meadows ".

In 1999 work to restore a memorial at the settlers' burial site turned up bones and forensic tests showed many in the group had been shot and not bludgeoned to death by the Indians, who had no guns.