A man who accuses his primary school vice-principal of sexual offences against him said he decided to alert police when the alleged abuser refused to settle out of court for $200,000, then accused him of extortion.

The pair, who had previously lived together, met on Nov 24, 2015 - 12 years after the alleged offences began - but instead of reaching an agreement, the vice-principal sent his former pupil a cease and desist order from a lawyer, a court heard yesterday.

On the second day of the 55-year-old teacher's trial, the 29-year-old alleged victim testified that the older man sent him a text message later that day which insulted his parents and told him to lodge a police report.

The younger man, a Singaporean who came here from China in 1999, alerted the police the next day.

The vice-principal is on trial for three counts of committing an indecent act on a young person and six of having carnal intercourse against the order of nature with the victim when he was a teenager. He has been suspended from his duties. The two men cannot be named due to a gag order.

Yesterday, the alleged victim testified that he did not want to inform the police about the case at first due to his responsibilities to the vice-principal's family.

He told District Judge Chay Yuen Fatt that he had helped in taking care of the older man's ill parents and his alleged abuser was also supporting the family financially.

Wiping away tears, he added: "If I reported, the whole family dynamics would change because (the vice-principal's) job would be affected."

The court heard that the victim met his future wife while on a group tour to Europe with the vice-principal in June 2013. He later told her about what the vice-principal had allegedly done to him. She advised him to move out from the home they shared and inform the police.

He moved out in 2013 to the woman's family home after lying to the vice-principal that his parents knew about the alleged sex acts.

He told Judge Chay that the vice-principal was apologetic when he heard this and told him: "Please don't report to the police. Otherwise, I would commit suicide."

In August 2015, the younger man bumped into the vice-principal's niece, whom he knew had dealt with sexually abused children. He decided to tell her about what her uncle had allegedly done. He said she told him to alert the police.

He later thought it would be a good idea to settle the matter without informing the police by asking for the $200,000 compensation.

He contacted the vice-principal, who agreed to meet him on Nov 24, 2015. When they met at a cafe, he said that the older man told him that somebody would send him the money and left. The alleged victim testified that a man handed him the cease and desist order after that.

The trial resumes today.