Federal and state police officers raided a group home in the western state of Michoacan and rescued 458 children who were forced to beg for money and were sexually abused while being held against their will in filthy conditions, Mexico's top prosecutor said.

Attorney General Jesus Murillo Karam said police also rescued 138 adults from the Great Family group home in the city of Zamora on Tuesday.

The residents were kept in deplorable conditions, fed rotten food, and made to sleep on the floor among rats, ticks and fleas and many of them were never allowed to leave the premises, Murillo Karam said at a news conference attended by top federal investigators and Michoacan Gov. Salvador Jara.

"I'm in utter dismay because we weren't expecting the conditions we found at the group home," Jara said.

Police detained the home's owner, Rosa del Carmen Verduzco, and eight workers for questioning, Murillo Karam said.

The investigation began after five parents filed complaints last year with authorities because they weren't allowed to see their children at the home, Jara said.

One parent was a woman who grew up and gave birth to two children at Great Family, which has been open for 40 years. She was allowed to leave when she was 31 years old, but Verduzco kept the two children, who had been registered under her name, said Tomas Ceron, head of the Criminal Research Agency at the Attorney General's Office.

Babies born at the home were registered in the founder's name, Ceron explained in a clip from the news conference on BBC News.

This prevented the biological parents from being their legal guardians and making decisions about their children's upbringing.

The parents were promised the children would be permitted to leave once they reached legal age of 18.

One mother said she was only allowed to see her son three times a year and that the home's owner demanded $2,800 to release him.

Veronica Gamina said that four years ago she took her then nine-year-old boy to the home because she had to work and couldn't take care of him.

Gamina says she has been trying to take her now 13-year-old boy home for a year but the owner first asked her to write letters and then demanded $2,800.

The 28-year-old restaurant worker said she went to authorities after hearing about the conditions inside the home from someone who escaped.

With files from CBC News