Phra Khru Sangkharak Saksit Kittiko, 40, now again known by his lay name Saksit Sonbanphaeo, was acting abbot of Wat Pa Suwatthanaram in tambon Lak Sam of Ban Phaeo district.
He was detained by a combined team of police and officials from the Social Development and Human Security Ministry on Wednesday, expelled from the monkhood and charged.
The senior monk was wanted on an arrest warrant issued by the Samut Sakhon provincial court for sexually molesting children under 16 years of age, sexual molestation using intimidation and forcing other people to perform obscene acts.
He was taken into custody in the temple grounds as he was about to go out collecting morning alms.
Pol Maj Gen Worawat Watnakhonbancha, commander of the Anti-Human Trafficking Division, said police investigators had evidence the suspect had sexually molested novices who were ordained during semester breaks, and temple boys. This included testimony from victims, parents and nuns at the monastery.
It is alleged the abbot confiscated the boys' mobile phones when he abused them, to prevent them taking photos or phoning other people.
However, some victims managed to take photos and to contact their parents, Pol Maj Gen Worawat said.
There were 19 novices, one aged 19 and the others all younger, and 10 temple boys at the temple. The youngest was 8-years-old, he said.
Pol Maj Gen Worawat said later that 10 novices and one temple boy had alleged they were sexually abused.
The acting abbot had commanded wide respect from residents, as a development monk who supported the education of children from needy families, he said.
The former Phra Khru Sangkharak had played a key role in developing the monastery 15 years ago and was about to be confirmed as the abbot before the sex scandal broke, Pol Maj Gen Worawat said.
Officials from the Social Development and Human Security Ministry were assisting the victims. The Office of National Buddhism would make inquiries whether other novices who previously stayed at the temple were also abused.
Mobile phones belonging to novices were found inside the monk's living quarters. Used condoms were found behind the novices' quarters. All were taken as evidence, Pol Maj Gen Worawat said.
Atchariya Ruangrattanapong, chairman of the Help Crime Victims Club Facebook page, alleged the victims' hands and legs were tied and they were sodomised. On occasions, novices had been forced to perform sexual acts among themselves while he watched, he alleged. Sometimes, outsiders had been invited to participate.
Mr Saksit denied all the allegations. He said he had been in the monkhood for over 20 years and made contributions to the temple. He did not know why he now faced such false allegations.
He was handed over to local police for legal action.