Interpol has issued an international wanted persons notice for Canadian school teacher Christopher Paul Neil as part of an investigation into the alleged sexual abuse of at least a dozen young Asian boys.

The international police agency, based in Lyon, France, issued the so-called red notice after Thai authorities issued an arrest warrant earlier Thursday as part of a global manhunt for Neil.

Keo Vannthan, Director of Cambodia's Interpol bureau, shows passport documents of Christopher Paul Neil at police headquarters in Phnom Penh, Cambodia, on Wednesday. Border guards across SE Asia are on alert for Neil.
(Heng Sinith/Associated Press)

The Interpol red notice seeks the arrest or provisional arrest of a wanted person with a view to extradition.

Christopher Paul Neil, 32, of Maple Ridge, B.C. is wanted on two counts of assaulting two boys at his Bangkok apartment, Thai police said.

Thai police said two Thai teenagers, who were 13 and 14 at the time of the alleged assaults, came forward Wednesday to testify against Neil.

Neil is believed to be in Thailand, where police are attempting to track him down through his network of friends and by putting border guards in neighbouring countries on alert.

Neil is the subject of an international manhunt sparked by Interpol's rare appeal last week to find a man who appeared in 200 photos posted on the internet depicting sexual abuse of a dozen young boys.

The image of the man in the photos was obscured with a digital swirl, but in a breakthrough, police computer experts in Germany unscrambled the photos and Interpol released them in a public appeal to find the subject of the three-year investigation.

Interpol released this photograph of Christopher Paul Neil taken at the Bangkok International Airport last Thursday.
(Interpol/Thai immigration authorities/Associated Press)

Interpol secretary general Ron Noble said the arrest warrant makes it easier to restrict Neil's movements.

"It's been one of the most significant developments for us. We've been pushing for this since last Wednesday to try to limit Mr. Neil's ability to move from one country to another," Noble told CBC Newsworld in an interview from Lyon, France.

Noble said the international police agency has found images of one of the alleged victims in its database.

Neil, who was teaching English in South Korea, is believed to be in Thailand after security cameras photographed him passing by Thai immigration authorities at Bangkok International Airport last week.

Border guards in Thailand and neighbouring countries are on alert.

"We are quite certain he is still in Thailand and we think we are moving closer," Thai police Col. Apichart Suribunya said Wednesday. "Even if he uses a fake passport to try to get out of the country, his pictures are already published everywhere."

"We are also trying to find more information and investigate his connections in Thailand that he made during his previous stay so we can get closer to him and his network of friends," he added.

The photo of Neil arriving in Bangkok was broadcast around the world Tuesday as Interpol and Thai police named him as their prime suspect.

With files from the Associated Press