STATEN ISLAND, N.Y. -- A $900 trillion suit.

That's trillion with a "t," and it's the amount in damages which a West Brighton woman seeks from the city for, she alleges, improperly placing her two sons in a Queens foster home more than three years ago.

Fausat Ogunbayo, 46, recently sued the city and its Administration for Children's Services (ACS) in Brooklyn federal court, claiming the defendants had violated both her civil rights and her children's by removing the boys from their home here in June 2008.

The children, then 12 and 10 years old, are now 16 and 13, respectively. They have been out of their mother's custody since being relocated to Queens.

Ms. Ogunbayo alleges she and her children have suffered "over three years of terror, horror, grievous harm, time lost, substantial economic hardship and injuries" due to their separation.

In removing the boys, the city contended Ms. Ogunbayo was mentally unstable and had refused treatment, said court papers. She allegedly suffered from hallucinations and delusions, and also left the boys at home alone for extended periods while she was working, the city maintained.

Ms. Ogunbayo, who is representing herself, has branded the allegations a "huge lie."

A recent appellate court ruling may provide her some legal ammunition.

Last month, the state Appellate Division, Second Department, in a separate legal case, vacated the Family Court finding of neglect against Ms. Ogunbayo.

There was no evidence, the appellate panel determined, the children were ever in "imminent danger" of harm despite Ms. Ogunbayo's refusal to acknowledge her mental condition.

"Proof of mental illness alone will not support a finding of neglect," unless there's a causal link between the parent's condition and actual or potential harm to the child, said the court.

In fact, the youngsters had "near-perfect" attendance in school and "were doing well, even thriving, academically," while in their mother's care, the appellate division said. In addition, the boys were up to date on their medical examinations and vaccinations, and their heights and weights were appropriate for their ages, said the court.

While the appellate ruling restored custody of her children to Ms. Ogunbayo, she alleges ACS has "refused" to return them.

A city Law Department spokeswoman yesterday said the children remain in ACS custody, because the agency has filed a new petition in Family Court.

Citing the pending litigation, the spokeswoman declined comment on the other allegations in Ms. Ogunbayo's lawsuit, but said a plaintiff's damages' demand "has no bearing on whether the case has any merit and no relation to actual damages, if any."

Ms. Ogunbayo told the Advance last night that the city is "treating me very bad and now they want to come around and lie against me."

The bottom line: She wants her children back.

According to court papers, ACS moved to take away Ms. Ogunbayo's kids after receiving several reports of suspected mistreatment in mid-2008.

In one, she allegedly told a doctor her children's skin was becoming darker each day, due to radiation. In another incident, she wrote her children's school that the FBI and Secret Service were out to get the boys, ACS said in court papers.

Ms. Ogunbayo insisted she was mentally stable, and the children were removed because she refused to seek "necessary treatment for her mental health issues," the agency contended.

ACS also maintained Ms. Ogunbayo endangered the boys by leaving them alone for up to seven hours after school and all day on weekends, said court papers.

In response, Ms. Ogunbayo submitted a November 2008 letter from the children's pediatricians, saying they seemed to be well cared for during the eight preceding years in which they were patients. Doctors also said they hadn't seen Ms. Ogunbayo behaving erratically.

She also provided handwritten letters from her sons saying they wished to live with their mom.

And court papers said her older son was having some problems with the law while in foster care -- he was arrested in Queens in August of last year for alleged marijuana possession.

In its ruling, the appellate court said evidence that Ms. Ogunbayo sometimes left her kids unattended for long periods was "vague and contradictory."

ACS failed to establish that any lack of supervision on her part created an impending risk to the children's health, safety, or mental or emotional condition, the court determined.

The panel also recommended that ACS provide -- and that Ms. Ogunbayo accept -- "appropriate services or referrals" to aid her reunification with her children, after more than three years apart.