A teenager who encouraged a 12-year-old boy to expose himself via a webcam - and threatened to "make trouble" if his victim refused - has been spared jail.

Sean Doncaster was given a community order and final warning after he admitted contacting the boy and possessing child pornography.

On Friday Kingston Crown Court was told Doncaster, from Morden, had befriended the 12-year-old using chat programme MSN messenger.

Prosecution barrister Tom Nicholson said in early 2010 Doncaster asked the boy whether he had ever had sex, asked the boy to touch himself and offered to pay £350 if he posed in his underwear. Doncaster also promised his victim an iPod if he agreed to his requests.

The unemployed 18-year-old later asked to meet up with the boy, and threatened to "make trouble" if he mentioned their conversations to other people.

The Kirksted Road resident, who had hoped to become an architect, used the alias Leon Jackson during some of the conversations.

The victim had seen Doncaster once in real life but did not known him. Doncaster was arrested on July 9 last year after the boy's stepfather found records of the conversations and called the police.

Officers later found child porn on Doncaster's laptop, including images of children being sexually assaulted by adults. There were also records of sexual conversations with other people, although their age was not known.

On May 4 this year, on the day he was due to stand trial, Doncaster admitted three charges related to the images and one of inciting a child to engage in sexual activity.

On Friday Judge Susan Tapping said he was potentially a serious sexual offender and was at a critical point in his life.

Handing down a community sentence, she said: "I want you to understand the serious position you're in, and that the court will give you this single chance to get things sorted out for the future."

He will be supervised for two years and forced to attend an education programme to prevent further offences. He was also placed on the sex offenders register for five years, and banned from contacting anyone younger than 16 years old.