An investigation is underway into a glitch in New Zealand's interbank payment system, which failed on Wednesday because of a faulty cable.



Thousands of payments were delayed early Wednesday morning when the Swift network, which processes information on payments between accounts, failed.



By 10am yesterday Payments New Zealand, which governs the system, said most transactions had been processed, although some bank customers were waiting until today for payments to be cleared.



The problem appears to have been caused by a faulty network jumper cable.



While it was quickly identified, Payments New Zealand was reluctant to restart the system immediately, with extensive testing conducted until last night.



Swift, which operates similar systems in more than 200 countries promised a ''thorough investigation'' into the problem.



In a statement, Switch's Asia Pacific chief executive Ian Johnston said the company was putting together a report for its customers in New Zealand, which will cover the cause of the problem and how to prevent it in the future.



''We regret that our customers and their customers have been inconvenienced and are closely working with the financial community in New Zealand to ensure normal service resumption,'' Johnston said.



Payments New Zealand chief executive Steve Nichols said his team was also preparing a report, which he hoped would be completed within the next 10 days.



Asked whether the failure of a component implied the system was not sufficiently robust, Nichols defended the Swift network.



''I need to gather all the facts before I make a clear statement on this, but I think the system is robust, but the fact that an event like this occurs is serious.''



He would gather the facts in the coming days which would put him ''in a better position to understand issues of resilience or robustness, or whatever''.