Former government trade official John Finnin placed an ad on Craiglist for sex with school boys in the Frankston area in April 2018, court documents show.

"School Boys Wanted - m4m" the title read.

"I am a 60 year old, good looking down to earth easy going guy who is looking for a young boy on a regular basis for some fun."

The now 63-year-old said in the online ad he was looking for "no one under or over 18 please", the documents reveal.

Instead a police officer posing as a 14-year-old named "Will Cooper" responded.

Despite quickly realising he was communicating with someone under-age the former Australian diplomat kept sending explicit texts.

"The messages you sent may clearly be regarded as grooming and are sexually explicit in nature," Judge George Georgiou said in delivering his sentence on Friday.

The former diplomat told the fictional 14-year-old he would teach him the "joys of gay sex" and arranged to meet with him at Seaford railway station.

The original advertisement also offered a reward for whoever was willing to sleep with Finnin.

However he wanted to confirm the boy's identity with a video call and called off the meeting after it didn't happen.

"If I don't hear back from you I'll delete all texts between us. Hope to hear back from you, but if not the very best of luck. Stay safe and take care," the final text read.

After he was arrested, Finnin told a psychologist he was "lonely and did not think about the consequences" of his actions.

The offences occurred two years and three months after the Irish-born accused spent seven years in jail for sex crimes against a boy.

He has been unemployed and was vilified in the community after his 2016 release, with one man assaulting him and calling him a pedophile, the court was told.

Finnin was jailed for three years but will be released after serving 14 months and paying $1000.

He must also comply with strict reporting conditions and has been put on the sex offender register for life.

Australian Associated Press