A former employee has admitted defrauding the Canterbury District Health Board in what's alleged to amount to more than $1 million over a five-year period.

The 50-year-old ex-admin worker, who has since left the Canterbury DHB, says she used the stolen money for online gambling.

She pleaded guilty to one representative charge of fraud at Christchurch District Court this afternoon.

However, the exact number of transactions and the total amount are disputed, defence counsel Phil Shamy said.

The Serious Fraud Office (SFO) say they found multiple fraudulent transactions between January 2013 and August 2018 amounting to $1,062,973.

Shamy wants to engage a forensic accountant to examine the SFO report.

If the defence and SFO prosecutors cannot agree on the amount, a disputed facts hearing to determine the amount of money stolen is expected to be held later. The case could spill over into next year.

The woman, who first appeared in court on July 4 this year and who has no prior convictions, has been granted interim name suppression and is due back in court on November 7. The reasons for suppression, which was opposed by the media, cannot be published at this stage.

A redacted summary of facts was released to media today which outlines her fraud.

It states that she had a "high level of independence and control in her role with minimal oversight".

However, the woman was caught fiddling the system earlier this year.

During an interview with the SFO in March, she owned up to taking CDHB money, diverting patients' cash into her personal bank accounts, and causing patients to deposit funds directly to her.

The woman also admitted falsifying CDHB documents, providing false bank account details to insurance companies, and using funds from CDHB patients to engage in online gambling.

A CDHB spokesman said it would be inappropriate to comment while the matter remains before the courts.