Children line up to enter a tent at the Homestead Temporary Shelter for Unaccompanied Children in Homestead, Florida. (AP Photo/Wilfredo Lee, File)

Immigrant advocates say the U.S. government is allowing migrant children at a Florida facility to languish in “prison-like conditions” after crossing the U.S.-Mexico border instead of releasing them promptly to family as required by federal rules.

A court filing Friday revealed conditions inside the Homestead, Florida, facility that has become the nation's biggest location for detaining immigrant children. A decades-old settlement governing the care of detained immigrant children calls for them to be released to family members, sponsors or other locations within 20 days, but the court filing accuses the government of keeping kids there for months in some cases.

The children detained at the facility said they longed to be released to their parents and other relatives in the United States and were allowed limited phone calls to loved ones. Some were also told to heed strict rules or it could prolong their detention or get them deported.

“At Homestead, children are housed in prison-like conditions and unnecessarily incarcerated for up to several months without being determined to be flight risks or a danger to themselves or others,” said the motion filed by the National Center for Youth Law and other organizations in federal court in Los Angeles.

Dozens of volunteer lawyers, interpreters and other legal workers interviewed more than 70 child migrants at Homestead during several visits over the past year. The U.S. Department of Health and Human Services does not allow news media to speak to children at guided tours of the facility.

A Honduran boy described arriving with an aunt at the Mexico border in December. She was deported and he was sent to Homestead, where he told attorneys he had been held for four months. He could speak to his mother in Honduras twice a week while waiting to be placed with another aunt in Virginia. He was punched in the face by a boy at the facility but said he didn't see a doctor or tell his mother, out of fear she would worry more.

“Already it is very hard. We both cry on the phone,” he told attorneys. “I have not seen my mom or any family for so long.”

The children's allegations come as officials struggle to accommodate increasing numbers of minors illegally crossing the U.S.-Mexico border. The Homestead facility, run by a private contractor, houses 2,200 minors and is expanding to add hundreds of beds.

The U.S. Department of Health and Human Services did not respond to requests for comment. The private contractor, Comprehensive Health Services, declined comment.

Many of the children are fleeing gang and domestic violence and will end up seeking asylum. Most are sent to live with sponsors once they are screened by the U.S. government, usually aunts or uncles or other relatives who are already in the country.

The court filing included testimonials from more than a dozen children who had been separated from parents last year before the Trump administration ended a policy that led to more than 2,700 children being taken from families. Others, who had crossed the U.S.-Mexico border in the past few months, came alone or with relatives such as aunts, uncles, siblings and were also separated and placed in government custody.

The Trump administration has long complained about the 1997 settlement, which generally means the government should release children in about 20 days.

The names of the children were redacted, but they testified being there for weeks, or months, without knowing when they would be released. A girl told attorneys she and her sister were at the same facility but kept in separate areas and only allowed to see each other once a week.

A 14-year-old boy from Honduras said he had problems videoconferencing with the social worker handling his reunification on two separate occasions, as the company began hiring clinicians and case managers to work long-distance.

“Sometimes there are problems with the Internet, and I have to cut my call short or not talk to her at all and return another time,” he told attorneys.

A Guatemalan girl said she didn't speak any Spanish, only her native Maya language of Q'eqchi, when she arrived, and she had troubles understanding her social worker.

In the same filings, a federal field specialist for the U.S. government's Office of Refugee Resettlement said the goal is “safe, timely release” but there can be delays, for example, when sponsors can't read and write. And when there's no proof of a prior relationship, the sponsor is automatically disqualified, the specialist said, adding “the bottom line is always safety.”

In several occasions, children were flown from Florida to Texas locations promising they would be reunited with a parent, only to be flown back and booked again into the facility.

A Guatemalan child expressed willingness to leave the U.S. voluntarily only to be told that a legal department would need to get involved.

“It is hard for me to understand what is preventing me from joining my family,” the child said.

A Salvadoran boy who said he left his country in January fleeing violence said children at the facility can't touch anyone or fight or they could get a report that will delay their case. He told lawyers that staff told them they would be deported if they tried to escape. He said he couldn't speak with his parents on his 17th birthday since he had already used one of his twice weekly 10-minute phone calls the day before.

“I miss them, and even though today is my birthday, it is hard because they can't call me and I can't call them,” he said.

Adriana Gomez Licon and Amy Taxin report for the Associated Press.