All the multi-layer glass panels in the 186m-high observation deck floor of Auckland's Sky Tower will be checked after the surface of one cracked, alarming tourists.
SkyCity Entertainment Group said the area where the "sacrificial" surface glass of the panel had cracked was cordoned off to ensure visitors' safety and to allow it to be fixed.
"In the interim a section of plywood will be installed to allow the area to be opened up to normal business use," a spokeswoman said.
"The panels are made of a specialist piece of glass that has to be cut to fit and will be installed in the next few days.
"As part of our normal maintenance, we will be routinely checking all of the other panels," the spokeswoman said in answer to Herald questions.
"The Sky Tower observation deck has remained open and [it] has been business as usual, so, no, the incident has not been off putting for tourists."
The architect who designed Auckland's Sky Tower has defended its safety.
"There's absolutely no problem with it at all," said Gordon Moller, of Moller Architects.
"It's a superficial layer designed to protect the [structural] glass underneath from scratching."
He said it was possible that the shattering of the protective surface layer could have been caused by something being dropped on the glass panel.
Moller said the Sky Tower was designed, to very stringent standards, to last for more than 100 years.
Its construction was completed in 1997.
Tourists spoke of seeing the glass shatter yesterday in one of the viewing panels in the floor of the tower's observation deck.
Visitors to New Zealand Bob Brauser user and his wife were nearby when the glass broke.
"[It was] very frightening having just 'pranced' over it gingerly overcoming and controlling that stomach queasiness that accompanies vertigo from such terrifying heights," he told the Herald.
"My wife was extremely terrified ... she commanded me to exit immediately and was most definitely concerned that something even more serious was about to occur."
The area has been blocked off and the damaged glass will be replaced.
After the incident, SkyCity Entertainment Group said the crack was superficial and not a cause for people to be worried.
It said the structural glass, which has two protective layers of glass, is 38mm thick and as strong as the surrounding concrete.