About 1500 people were at the concert on Friday when the balcony gave way. Photo: Gregor Richardson

The Government has ordered an investigation into whether the balcony of a Dunedin flat that collapsed, injuring 18, met building standards.

Nick Smith

Two people remain in Dunedin and Christchurch hospitals in a serious condition after a balcony at a block of flats at 598 Castle St gave way on Friday night.

One is a 19-year-old Otago University student who has broken her back in three places. Her family fears she may never walk again.

• Teen breaks back in balcony collapse

The woman's grandmother, who did not want to be named, has told the Herald on Sunday her granddaughter had suffered multiple fractures.

When asked if she had concerns about the girl being able to walk again, the woman said: "I think the surgery went well, but the outlook's not great.

"She has broken her back in three places. It's pretty horrible. I'm sure she'll pull through but she's got a long road ahead."

Sixteen other people injured were discharged from hospital on Saturday.

Building Minister Nick Smith announced this afternoon that he had requested the Ministry of Business, Innovation and Employment investigate and prepare a report on the collapse, which occurred at a Six60 gig that was privately held.

"We need to establish whether the balcony that collapsed was up to the standards required by law under the building code," Dr Smith said.

"Structural failure of buildings are rare in New Zealand but every incident of this sort needs to be thoroughly investigated to establish whether there were failings and whether our building systems are working as they should.

"The investigation needs to look into whether the design, construction and maintenance of the balcony was up to the required standard, and to establish why it collapsed."

It was possible the balcony met standards, but the large number of students on it was in excess of what the building code required, Dr Smith said.

"I am open to all possibilities but want to ensure we do everything possible to avoid these sorts of building accidents.''

The ministry would be working with the Dunedin City Council in its investigations, and Dr Smith expected to receive a preliminary report on the balcony collapse by the end of this month.

Dunedin mayor Dave Cull welcomed the Government investigation this afternoon.

Mr Cull said it should go beyond looking at whether the balcony met the standard, and examine whether the current standards were adequate.

''It should look at not only whether this balcony was built to standard, but whether the standards are robust enough.''

A WorkSafe New Zealand spokeswoman said the department would decide whether to launch an investigation and were working with police.

Richard McKnight, a shareholder in the company that owns the damaged flat, told the Otago Daily Times on Saturday that Ogato Investments Ltd had owned flats in Castle St since 2001.

Mr McKnight said he was not aware of any previous problems with the balconies, and would be "working through" the situation with the property manager.

"I'm obviously sorry for the people who were injured," he said. "I'm obviously thinking about the poor students who were hurt."