The mothers said the letter was mailed Saturday. Perry spokesman Robert Black said Sunday that he had not seen the letter and couldn't comment.
Some 416 children were rounded up and placed in temporary custody 11 days ago after a domestic violence hot line recorded a complaint from a 16-year-old girl. She said she was physically and sexually abused by her 50-year-old husband.
The one-page letter, signed by three women who claim they represent others, says about 15 mothers were away from the property when their children were removed.
"We were contacted and told our homes had been raided, our children taken away with no explanation, and because of law enforcement blockade preventing entering or leaving the ranch, we were unable to get to our homes and had no-where to go," it said. "As of Wednesday, April 9, 2008, we have been permitted to return to our empty, ransacked homes, heartsick and lonely."
The mothers said they want Perry to examine the conditions in which the removed children have been placed.
"You would be appalled," the letter said. "Many of our children have become sick as a result of the conditions they have been placed in. Some have even had to be taken to the hospital. Our innocent children are continually being questioned on things they know nothing about. The physical examinations were horrifying to the children. The exposure to these conditions is traumatizing them."
Asked about claims that children were hospitalized, state Child Protective Services spokeswoman Marissa Gonzalez said she had not seen the letter and would have to review it before commenting.
A judge will decide this week whether the children will remain in state custody or return to their families. Hearings are scheduled for Monday and Thursday.
On Sunday, state officials enforced a judge's order to confiscate the cell phones of the women and children removed from the ranch.
The order was sought by attorneys ad litem for 18 FLDS girls in the state's custody, Gonzalez said.
Reading from the court document, Gonzalez said attorneys reasoned that cutting off communications would "prevent the possible tampering of witnesses."
It was unclear how many phones were taken Sunday. Gonzalez did not know whether the document could be released.
Affidavits filed by child protection workers said they found a pattern of abuse at the Yearning for Zion ranch in Eldorado, about 45 miles south of San Angelo.
The 1,700-acre fenced ranch, a former game preserve, was bought by the FLDS in 2003. A number of large dormitory-style homes have been built, along with a small medical center, a cheese factory, a rock quarry, a water treatment plant and a towering, white limestone temple.
The children are being housed in San Angelo's historic Fort Concho and at the nearby Wells Fargo pavilion. About 140 women from the ranch are also with the children, although they are not in state custody.
On Saturday, five FLDS women staying at the fort told Salt Lake City's Deseret News that the temporary shelter is cramped - cots, cribs and play pens are lined up side by side - and that many of the children are frightened.
Authorities said they have not yet located the teenage mother whose call for help triggered the raid at the ranch.
Texas authorities have issued an arrest warrant for the alleged husband, a man identified as Dale Barlow of Colorado City, Ariz., one of two communities on the Utah-Arizona border that have been the traditional home base of the secretive church.
Texas Rangers met with Barlow and his probation officer in St. George, Utah, on Saturday but did not arrest him. Barlow is serving three years' probation after pleading no contest to sexual misconduct with a minor - a teenager to whom he was spiritually married.
"As for Mr. Barlow, we are continuing to look into whether we have a warrant on the correct person," said Tela Mange, spokeswoman for the Texas Department of Public Safety. "Until we are able to locate and talk with the complainant it will be difficult for us to know for certain the correct identity of the alleged suspect."
The sect practices polygamy in arranged marriage that often pair underage girls with older men. The faith believes the practice will brings glorification in heaven. The mainstream Mormon church, the Church of Jesus Christ of Latter-day Saints, does not practice polygamy.
