A full field evacuation after a fire alarm goes off at University Oval.

Play resumed after a fire alarm resulted in University Oval being evacuated, with the test match between New Zealand and South Africa in Dunedin delayed by about 20 minutes.

Both teams were herded to the middle of the pitch about 5.10pm as sirens sounded, while spectators in the main stand and then on the banks were evacuated.

But soon after, everyone on the grounds was asked to leave, including the players, TV crew and media, support staff, and spectators.

JOHN COWPLAND/PHOTOSPORT Play at University Oval in Dunedin has been delayed after a fire alarm.

READ MORE: Black Caps v South Africa - day three

Stuff cricket writer Mark Geenty said the media were evacuated from the ground for about two minutes before being told they could go back in, after the fire department had checked out the grandstand and given it the all clear.

The fire service understood the grandstand fire alarm was caused by steam.

Play resumed on the third day about 5.30pm, but ended early due to poor light.

South African spinner Keshav Maharaj, who took his first test five-wicket bag in New Zealand's innings, revealed he was no stranger to such a bizarre incident.

He said the same thing happened during the South Africa A game against Australia A in Townsville last year.

"Surprisingly, yes. During an SA A tour last year we were sitting in the changing rooms and the fire alarm went off. So nothing new for us," he said.

"When the boys went on there was not much of a crowd left so disappointing for them as it was for us."

Black Caps wicketkeeper BJ Watling said the worst part was that the crowd atmosphere fizzled out when play resumed.

"That was definitely something different. I can't say I've ever had that happen before. The biggest shame was that the crowd left and it was quite a good atmosphere today. It was pretty cool to be out there," Watling said.

The only situation Watling could liken it to, was during a West Indies tour in 2012.

"I remember a situation where we had an early drinks to watch the Jamaicans run in the 100m final [London Olympics 2012]."