The Crime Suppression Division (CSD) has added a Suphan Buri temple abbot to a list of arrested criminal suspects in its latest operation to "purify" Buddhism.

The CSD announced it had caught 18 monks accused of various crimes, including murders and sexual harassment.

CSD chief Chiraphop Phuridet vowed his agency will make 2019 a year of "sweeping temples clean" by further unmasking criminals-turned-monks nationwide.

Investigators are identifying who they are and tracking down where they were ordained, getting clues from piles of arrest warrants.

"I've ordered CSD officers to conduct cross-country investigations by looking at each arrest warrant," Chiraphop told the Bangkok Post.

The suspects cannot simply use the monkhood to shield themselves, he stressed. "I want to purify the religion, so people will trust monks again."

The latest case in Suphan Buri, the 19th on the list, came to light after police found Phra Sangkharak Kanatathamo, abbot of Wat Ro Charoen in Bang Pla Ma district, had escaped charges of attempted murder and illegal possession of weapons for 15 years.

The 40-year-old monk is actually Paphonsan Phetphun who, along with his friends, allegedly shot a rival in Nakhon Si Thammarat's Tha Sala district in 2006, according to the CSD.

A monk in a temple in the northeastern province of Kalasin had been also on the run for a charge of attempted murder for 15 years, the CSD said.

The alleged wrongdoing of Phra Bunchu, or Bunchu Champasi, 48, after he, along with a female suspect, injured a rival with a broken bottle during a dispute in Rayong in 2007 was totally unknown to his followers in Kalasin.

"Temples and people dealing with ordination must carefully check the criminal backgrounds of prospective monks," Chiraphop said.