DAUPHIN, Man. -- Two Manitoba brothers have been sentenced to 16 months in jail after what a judge called a "relentless attack" of cyberbullying and sexual exploitation designed to "exploit, demean and humiliate" a 14-year-old girl.

Judge Donald Slough said a friend of the brothers met the girl on Facebook a year ago. In his written sentence released Thursday, Slough said the man told the victim to send him nude pictures or "he would do something to her."

When she sent him a picture of her exposed breasts, the man demanded she send more explicit pictures or he would send her nude picture to everyone in the community, Slough said. She complied.

The brothers, who were 17 at the time and cannot be named, found out about the pictures and started harassing the victim, Slough said.

"The communication was intense and relentless, occurring both day and night," the judge wrote. "The accused, acting in tandem, alternatively flattered and abused the victim, demanding progressively more explicit images; instructing the victim as to what sexual acts she was to perform and digitally record."

The brothers distributed the photos through social media, Slough said. The victim's parents discovered the abuse after noticing a change in their daughter's behaviour and went to police in January.

The brothers were arrested in May and pleaded guilty to four charges including sexual touching and possession and distribution of child pornography. Both have expressed "rather limited" remorse, Slough wrote. One brother said tormenting the victim was "fun but now feels it was stupid."

Slough said the impact on the 14-year-old has been "devastating and long-lasting." The girl went "from being happy to being deeply troubled."

"Ten months after being victimized, she is still frightened and demonstrating symptoms of extreme anxiety," Slough wrote. "Her reputation in the community has been damaged and she has been ridiculed at school.

"Given the difficulty in controlling the use of images once they enter cyberspace, the harmful impact on the victim may well be long term."

Experts say this kind of "sextortion" is becoming more common. The Canadian Centre for Child Protection recently warned it is seeing an alarming increase in the number of teens who are sharing sexual images of themselves and then being extorted, sometimes for money.

Signy Arnason, associate director at the centre, said this case is one of the more severe because of the age and tactics of the perpetrators.

"It's quite an extreme case when you're talking about youth engaged in this behaviour," she said. "It's deeply troubling."

The parents of Amanda Todd, a 15-year-old in British Columbia, say she committed suicide in 2012 after being extorted for two years. She exposed herself while on a web chat and the image was used to blackmail her into putting on another "show" online. She eventually posted a heartbreaking, nine-minute video online detailing her torment before she killed herself.

The suicide of Rehtaeh Parsons, another cyberbullied teenager in Nova Scotia in 2013, turned a spotlight on the issue. Her parents established an organization, the Rehtaeh Parsons Society, to address the prevalence of cyberbullying, youth sexual violence and the distribution of images among young people.

Jail sentences for those found guilty of such offences is a good deterrence, Arnason said. But she added that parents need to talk to their children about sexual exploitation online.

Children need to feel comfortable coming to their parents when they run into trouble because complying with threats from tormenters rarely puts an end to the bullying, she said.

"It's very, very challenging to stay on top of what kids are doing. You've got to keep those lines of communication open."