A paediatrician who achieved national recognition for his research into near-death experiences involving children may have been experimenting on his 11-year-old stepdaughter by waterboarding her, according to US court documents.

The possible link between Dr Melvin Morse's research and the waterboarding claims was revealed in an affidavit for a search warrant for Morse's computers. The document was obtained by The Associated Press.

According to the affidavit, Morse, 58, brought the girl "to a possible near death state from the simulation of drowning".

"This 'waterboarding' that he has performed ... would fall into the area of study he practises," police said in the affidavit.

"It is logical that he has therefore written about and/or researched the topic of 'waterboarding'."

Joe Hurley, a lawyer for Morse, said the idea that he was experimenting on his own daughter was "the sheerest of speculation".

Morse, who faces a preliminary hearing tomorrow on felony child endangerment and conspiracy charges, has written several books and articles on paranormal science and near-death experiences.

He has appeared on TV to discuss his research on out-of-body experiences. His website, http://spiritualscientific.com, is strewn with commentary about God, love, family and death.

Morse told the Associated Press on Monday that the charges against him were an overreaction from authorities who were criticised in the wake of a child sex abuse scandal involving another paediatrician.

He said he was the victim of "post-Bradley hysteria", a reference to doctor Earl Bradley, who was convicted a year ago and is serving 14 life sentences for sexually abusing scores of his young patients over more than a decade.

Following Bradley's arrest in December 2009, Delaware state officials ordered investigations into how he was allowed to continue practising medicine for years despite suspicions that he was molesting his patients. Politicians passed several new laws toughening requirements for police, healthcare workers and others to report suspected child abuse.

The allegations of waterboarding came after Morse was accused of grabbing his stepdaughter by the ankle in July and, as her six-year-old sister watched, dragging her across a gravel driveway. He was arrested on July 13 on misdemeanour endangerment and assault charges and released on bail.

When the older girl was interviewed last week, she told investigators that her father disciplined her by holding her face under a running tap at least four times since 2009, a punishment that she said her father called "waterboarding".

Waterboarding simulates drowning and it has been used in the past by US interrogators on terrorism suspects. Many critics call it torture.

State police said the girl's mother, Pauline Morse, witnessed some of the waterboarding but did not stop it. She is also on bail.

Melvin and Pauline Morse were both charged with felony child endangerment and conspiracy.

"All of these things are very absurd, except that Delaware has really had the trauma (of Bradley)," Morse said.

Morse ended the interview before he could be asked directly about the waterboarding allegations.

Mr Hurley has raised doubts about the girl's claims and described the waterboarding description as an "attention-getter" by authorities, based on an allegation from an 11-year-old who he said had made a false abuse claim against a family member before.

"I have no doubt but that the Bradley phenomenon has its fingerprints all over the sensationalisation of this situation," he said.

State officials suspended Morse's medical licence after his arrest last week.

Morse, who was released from custody on Friday after posting 14,500 dollars' secured bail, claimed he was "the first doctor to blow the whistle on Earl Bradley".

He said he warned state officials in 2007 that Bradley was using saline solution to give fake vaccines to his patients, though the officials said they never received a report from Morse until after Bradley was arrested in 2009.

"I reported that, and I'm the only Delaware physician who had the courage to testify for the Bradley victims," said Morse, claiming that he gave a deposition in the Bradley case.