SYDNEY - A former Canberra school teacher accused of grooming a fictitious 14-year-old New Zealand girl for sex said he engaged in "reprehensible" online chats to escape his lonely life.

Giving evidence in his trial at the ACT Supreme Court, Murray Colin Stubbs yesterday described his "disgusting and inappropriate" conversations with "Roxanne" as pure fantasy.

The 45-year-old father of four said he never intended to meet the teenager who was actually a New Zealand detective.

Stubbs pleaded not guilty to communicating online with a person under 16 with the intention of procuring her for sex and an alternative charge of using the internet in a way that reasonable persons would regard as being offensive.

He was arrested when he went to the Jolimont interstate bus terminal in Victoria to meet the girl on January 21, 2008 - five months after they first met online.

The Canberra Times newspaper reported Stubbs told the jury that the sexual conversations he conducted from an internet cafe during his lunch break were "imaginings".

"She was an escape from the unhappy reality of that time, she was a daydream I could go to," he said.

Stubbs told the court he felt guilt, fear and self-disgust at the "morally wrong" exchanges and tried to end them one month after they started, but was too weak.

"She had become someone who showed an interest in me .... I seemed to mean something to her and that meant something to me," he said.

Under cross-examination he said he taught the girl to masturbate within two weeks of their first online meeting because he regarded her willingness to engage in sexual acts as an indication of the trust and acceptance he craved, and thought she might enjoy it.

"I know that sounds reprehensible but that is the truth," he said.

Stubbs said he drew boundaries between the online and "real" world and would never seek a physical relationship with someone he had met on the internet.

Prosecutor Sara Cronan said Stubbs had requested the girl's phone number 30 times and asked if she would let him perform certain sex acts on her on at least 22 occasions.

Stubbs' lawyer Shane Gill characterised his client as a "pathetic, damaged man" who ultimately did not seek to have sex with the girl when the opportunity arose.

On the day of Stubbs' arrest, his wife drove him to work at the Department of Education, Employment and Workplace Relations and arranged to pick him up in the afternoon.

Stubbs told the jury that he was meant to collect the girl from Canberra Airport that afternoon but lied and said he had a meeting in an attempt to avoid her. He said that he only went to the bus terminal because he did not want to let down a 14-year-old.

Stubbs said he had told a colleague he would only be gone for 20 minutes.

The jury was considering its verdict today.