Auckland Mayor Phil Goff has launched a stinging attack on KiwiRail after a second signal failure in the past five days brought the city's trains to a halt.
Commuters had their journeys delayed following the failure, which saw trains halted for half an hour this morning.
Mr Goff took to Twitter to express his displeasure at the situation, which was the third such incident in 2019.
"A second KiwiRail signal failure on Auckland’s network is not good enough," Mr Goff wrote.
"I have asked KiwiRail for more information and sought assurance from its chair Greg Miller that infrastructure is fit for purpose."
KiwiRail's Todd Moyle told Stuff they were trying to identify the cause of the signalling fault.
The fault lasted 28 minutes.
"We apologise for any inconvenience," he said.