The Oxon Hill woman found caring for 54 children in her home last week had been ordered as far back as 1988 to stop providing unlicensed day care, a Maryland child-care regulator said yesterday.

Nannie Mary Pressley had been sent two cease-and-desist letters before receiving her third Thursday. After receiving the first two letters, she told child-care authorities she would attempt to get a license, but no record can be found that she obtained one, said Roberta Ward, assistant director of the state Office of Child Care Licensing and Regulation.

Without search warrant powers, child-care regulators had been unable for years to confirm persistent complaints that Pressley was operating without a license. After yet another complaint, regulators sought police help in the case last month.

"If this case shows anything, it shows how desperate parents are for child care and how difficult it is to take action against unlicensed day-care providers," Ward said.

No criminal charges have been filed, but Pressley was served with a letter ordering her to stop providing child care in her home. The case has been referred to the Prince George's County state's attorney.

Ward declined to specify the nature of parental complaints because her agency is preparing to seek an injunction to keep Pressley from reopening.

Pressley first came to the attention of child-care regulators in 1987, Ward said. After a parent complained, regulators visited the neat, two-story brick house and found three children who Pressley said were her grandchildren.

Regulators received a second complaint in September 1988 and a month later wrote Pressley to tell her to stop operating an unlicensed day-care center. Pressley told regulators on Oct. 19, 1988, that beginning on Dec. 3 she would attend the training course required for licensing, Ward said.

Twice, in December 1988 and the following month, regulators responded to parental complaints by making unannounced visits to Pressley's home. Each time, they were denied entry, Ward said.

In February 1989, the regulators sent a second cease-and-desist letter, she said.

Pressley attended an orientation session to get a license on March 15, 1989, but by August authorities were receiving new complaints that she was operating an unlicensed service.

Regulators finally sought police help when complaints surfaced again last month. A police officer, working undercover, also had difficulty confirming the complaints because Pressley allowed her to see only the first floor, Ward said.

Police and regulators jointly visited the home Thursday and discovered a lone teenager tending 54 children under the age of 10. Nine were infants in car seats.

Pressley said Friday that she had been licensed several years ago to provide child care but returned her license after becoming ill.

She admitted, however, that she was caring for children without a license when Prince George's police and child-care regulators entered her house in the 5100 block of Wheeler Road on Thursday afternoon.

Pressley, 53, said that she usually has about 20 children and that the larger number was the result of a birthday party. She said she had left the house briefly to buy party supplies.

Licensed day-care providers said it is too easy for their unlicensed counterparts to operate illegally.

"I'm surprised they found so many children in the home, but I'm not surprised the person was unregistered," said Diane Abdullah, president of the Prince George's Family Day Care Association.

"There hasn't been a lot of emphasis put on the unregistered provider," said Abdullah, a licensed day-care provider for 14 years.

Abdullah said unlicensed day-care providers outnumber licensed workers by four to one and typically can underprice licensed workers because they do not have to meet rigorous state standards.

"The unregistered providers hurt our business," Abdullah said.

Ward said at least two licensed day-care providers in Pressley's neighborhood have room for more children. Ward said Pressley's service apparently was popular because she used a van to pick up and drop off children.

People licensed to care for children in their homes are permitted to have no more than eight children if they are classified as a "provider" and no more than 20 if they are classified as a "center." State law also prohibits providers from having more than two infants per adult employee.

In Maryland, it is a misdemeanor to operate a day-care center without a license. Violators are subject to a $500 fine. Felony charges are possible if unsafe conditions are found.