(CNN) An American Catholic priest has been arrested in the Philippines -- and charged in US federal court -- on suspicion of sexually abusing boys in the Southeast Asian country where he's lived for decades, authorities in both nations announced.

The Rev. Kenneth Bernard Pius Hendricks, 77, originally from Cincinnati, was arrested Wednesday in the Philippine city of Naval after several alleged victims came forward to Philippine and US investigators last month, authorities said.

Though court documents filed in late November cite five accusers, a total of 10 accusers have now come forward in the Philippines, alleging Hendricks sexually abused them when they were boys, US Homeland Security Investigations Special Agent Steve Francis said Thursday in Cincinnati.

Because Hendricks also spends parts of the year in the United States, investigators are asking the public in both countries for information about the priest.

"It's horrifying ... abusive conduct," US attorney Benjamin Glassman said Thursday about the allegations in the Philippines. "It's grooming children -- young children -- that are interested in being involved in church activities and taking those kids and sexually abusing them."

"He befriended them, he would invite them to his residence" before engaging in progressively intimate contact, sometimes including oral and anal sex, Glassman said.

US law criminalizes certain illegal sexual conduct by American citizens abroad. Hendricks is charged in federal court in Cincinnati on a count of engaging in illicit sexual conduct in foreign places , punishable by fines and/or up to 30 years in prison.

Hendricks was being held in a Philippines Bureau of Immigrations holding facility in Manila, the bureau said. His attorney in the Philippines, Mario Opeña, told CNN that the priest maintains the allegations are false.

"As far as Father Hendricks is concerned, the allegations are not true and he will prove his innocence in court," Opeña said.

How the investigation started

Hendricks has been a priest in Naval, a city of about 50,000 people in central Philippines, the country's Bureau of Immigration said.

He was ordained as a priest in the Philippines after arriving in the country in the 1960s, said the Rev. Benjamin Pantas, spokesman for the Diocese of Naval.

The Naval diocese is conducting a parallel, independent investigation, Pantas said.

Of the allegations cited by the five accusers in a probable cause affidavit filed in court, the earliest dates to 2009. The accusers' ages at the start of the alleged abuse range from 7 to the teens, Glassman said.

The Philippine National Police began investigating around November 6 when two accusers, including a young man, came forward, the affidavit says.

Among the man's allegations, according to the document:

• Hendricks began sexually abusing him around 2009 when he was a 12-year-old serving as a sacristan in a church in Naval. Hendricks first kissed him on the lips while the boy was cleaning the church.

• Hendricks would beg him to sleep at the priest's home, and the accuser believed he had no choice. The priest would insist that they bathe together, and the priest would have oral and anal sex with him.

• Hendricks would molest him alone or with several other boys who "resided with Hendricks during that time."

• Hendricks said they "would both go to jail" if the abuse was reported to authorities.

• The abuse stopped when the accuser was 15, after he contracted a sexually transmitted disease.

Another of the accusers alleged that Hendricks had anal sex at least a dozen times and oral sex more than 30 times, the Cincinnati US attorney's office said.

It's not immediately clear when or how the US Homeland Security Investigations agents got involved. But HSI agents interviewed the adult accuser and four other accusers November 26-28, the affidavit says.

'I ... will have to probably really resign, retire now'

HSI received a recorded conversation, purportedly between Hendricks and the adult accuser in November, in which the two apparently discuss the accuser having talked to police, the affidavit says.

In the recording, the priest said he's "waiting for the fallout," according to the affidavit.

"There will be a meeting and then it will be decided, you know, what your parents want to do about anything. Do they want to try ... to press charges ... but that's between them and the bishop," Hendricks said, according to the affidavit.

"They will decide, ask you what your decision is, what you're going to do, whether there will be a case or not or whether, you know, a settlement, I don't know. But as far as after that, I don't know what's going to happen. I really will have to probably really resign, retire now," the priest said, according to the affidavit.

Eventually, the affidavit says, the accuser asked whether Hendricks admits to having sex with boys.

"It's already blottered," Hendricks said, apparently referring to the accuser's conversation with police. "You put it on a blotter. Will I lie? It was a mistake on my part. Should have known better than trying to just have life," the priest said, according to the affidavit.

'Other children may have been impacted'

Glassman, the US attorney, said Hendricks is not accused of abusing anyone in the United States, but investigators will explore the time he has spent in his native country.

Hendricks would spend several months a year in the United States -- likely in the Cincinnati area, after flying from the Philippines into Los Angeles, Glassman said.

The federal prosecutor said he didn't immediately know exactly where or how Hendricks would spend his time in the United States. But the affidavit says bank records indicate Hendricks has a residence in Cincinnati.

"We want to find out: Are there any victims in the United States -- in Cincinnati, in Ohio, Los Angeles or wherever?" Glassman said during a news conference Thursday in Cincinnati. "(We want to) hold Father Hendricks accountable for any sexual abuse of children here, just as we want to hold him accountable for any sexual abuse that he's committed in the Philippines."

Francis, the HSI agent, said: "We believe there is a high probability that other children may have been impacted by his alleged actions."

Asked whether the Philippines would want to put Hendricks on trial there instead of extraditing him to the United States, Glassman said: "That is something we are working out with them right now."

Hendricks was not a priest of the Archdiocese of Cincinnati, archdiocese spokesman Mike Schafer said.

The priest as listed on the archdiocese's website as being a missionary in the Philippines.

But Schafer, in email to CNN, wrote that Hendricks "is not 'assigned internationally by the Archdiocese of Cincinnati to mission work.'"

"Hendricks is not, nor never has been, a priest of the Archdiocese of Cincinnati. He was ordained to the priesthood in the Philippines to serve in a diocese there," Schafer wrote.

Toni Cashnelli, communications director for the Franciscan Friars, Province of St. John the Baptist in Cincinnati, said Hendricks was a brother with the Franciscan Friars.

He made temporary vows in 1962, solemn vows in 1965 and in 1986 asked to be released, Cashnelli said. She said she didn't have a record of why he requested to leave.