A system failure responsible for bringing the production of Australian racing information to a standstill will be the subject of an internal investigation.

Racing Information Services Australia (RISA) pledged on Tuesday to get to the bottom of the ongoing glitch which has created havoc with racehorse trainers, jockeys, racing form providers and other industry professionals.

The outage first affected the release of fields for Wednesday's racing as well as entries for Thursday, Friday and Saturday race meetings.

"A complete, thorough and forensic review commencing today - will be undertaken to investigate every aspect of the failure and what measures can be further put in place to try and negate any such recurrence," a statement on the RISA website said.

RISA's systems were forced offline on Monday after scheduled maintenance on Sunday night went wrong.

Chief executive Myles Foreman said the system had not been the target of a cyber-attack from hackers.

"It was certainly nothing external. We were in the process of system maintenance," Mr Foreman told Melbourne radio station RSN.

RISA has manually processed scratchings, nominations, acceptances and stable returns, which will be entered once the system is operational.

The failure has had ramifications for trainers attempting to put horses in the right races as well as book jockeys for the weekend.

"It's made placing horses very difficult," Sydney trainer Anthony Cummings said.

"We haven't had weights, we haven't had fields and all the things we need for the normal decision-making processes to take place."

Mornington-based Jason Warren said he was also affected by the delays.

He hasn't been able to lock jockeys in for rides because he doesn't know what weight his horses will be carrying.

"It's just made it a little harder to book jockeys," Warren said.