Blenheim District Court heard how a woman repeatedly asked a man for money in exchange for not going to police to say that he raped her. (FILE PHOTO)

A woman has blackmailed a man with rape claims in exchange for money, saying he would rather pay her money than end up in jail, a court has heard.

Joanne Lee Kerr, 33, had known the man about four months when she messaged him asking for money so she could get a prescription filled at the pharmacy on December 10 last year.

The man said he did not have enough money.

A few days later, she messaged him again, saying she needed money for Christmas presents.

The man gave her $220.

Over the next week Kerr repeatedly messaged him asking for more money, but the man repeatedly told her he could not spare any.

He messaged her on December 21, saying he would give her $120 if she promised to never contact him again.

Kerr agreed and he transferred the money into her bank account that day.

The next day, Kerr messaged him and said if he wanted to get rid of her for good he would need to transfer another $100 into her account.

The man refused.

Kerr said if he did not put $200 into her bank account, she would go to the police and say he raped her.

She also said she would tell everyone she knew, and write on Facebook, that he was a convicted sex offender who preyed on young girls.

The man tried to negotiate with her, and agreed to pay her $120 a week for the next year, starting next week.

Kerr said she needed $100 straight away, or she would tell his parents about the allegations.

He said he did not have enough money, but she raised her demand to $200.

The man transferred $50 into her bank account to stop her carrying out her threats.

The following week, Kerr messaged the man, demanding $220 or she would go through with her threats, saying "You would rather pay me $220 than go to jail for rape".

Throughout the day, she sent repeated demands to the man, saying "You won't last long in jail, I've got family in there for murder".

The man was so afraid he went to the police and reported Kerr's actions.

When spoken to by police, Kerr admitted threatening the man, but said it was just a joke and she was not going to go through with her threats.

Kerr admitted a charge of blackmail at the Blenheim District Court on Monday.

Her lawyer Rennie Gould said Kerr had a history of addiction and dishonesty but was "doing quite well".

"It might be a case of two steps forward, one step back."

Judge Richard Russell said he was familiar with Kerr's history.

"I know all about Ms Kerr, and she knows all about me.

"I have to say, I'm disappointed to see you back here. Blackmail is a serious charge. You might have thought it was a joke, but I don't, and I don't think he did either."

Judge Russell ordered a pre-sentencing report and a drug and alcohol report, and Kerr's home would be assessed for an electronically monitored sentence.

Kerr was convicted and remanded on bail to April 10.