Auckland train services were interrupted morning due to a KiwiRail signalling issue - the second time this has happened in a week.

Photo: RNZ / Laura Tupou

Commuters were stranded because the trains had to stop while the problem was sorted out.

Scheduled buses were accepting purchased train tickets and AT HOP cards, Auckland Transport said.

Trains started moving again after about half an hour, although the Onehunga Line was still suspended for some time afterwards. Trains on that line have now resumed.

Eastern, Western and Southern train lines are now running as normal.

It's the second signal failure in a week.

The Auckland rail network was shut down by a similar issue on Friday morning, when the system failed at 11.15am, stopping all trains on the network for an hour and a half.

In a tweet, Auckland Mayor Phil Goff said a second signal failure was "not good enough".