Hot air and gas has rushed up a small bore shaft which has broken through into the underground New Zeland coal mine where 29 miners remain trapped.
NZ Energy Minister Gerry Brownlee has confirmed that engineers have broken through with a 150mm bore hole at the Pike River Coal Mine near Greymouth on the South Island.
The miners, including two Australians, have been trapped since an explosion in the mine on Friday.
"It had hot gas rushing up it and a lot of hot air as well," Mr Brownlee said. "It will give a very good picture of what the gas state is in the mine and also the heat state. They are looking for a heat source.
"It is very significant information to the rescue planning," he told NewstalkZB, It is hoped a camera and listening device can be lowered into the main access tunnel.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Bomb disposal robot restarted
A bomb disposal robot which malfunctioned earlier in the week has restarted and been sent further down the shaft to check the tunnel and toxic gas levels.
Fluctuating gas levels have made it unsafe for human rescue teams to enter the shaft. It's believed a second robot also has been sent into the tunnel and another has arrived from Australia.
Families kept away from site
Meantime the families of the miners say officials are keeping them away from the site. Laurie Drew, whose 23-year-old son Zen is among those trapped says relatives are beginning to get angry about the lack of information from officials.
"A lot of us family members want to be on site regardless of what way things turn out," Mr Drew told a small group of reporters on Wednesday morning.
'Not safe' to send rescuers underground
Police said safety concerns were stopping access to the remote mine on the west coast of the South Island.
On Tuesday afternoon, family members were shown a sobering 52-second video of the effect of the powerful blast captured at the entry to the coal mine.
The hazy CCTV footage showed grey stone dust blowing out of the mine and a metal sheet violently flapping as the blast occurs at least 2.5km in to the shaft. Pike River Coal CEO Peter Whittall told reporters families had not questioned why they haven't seen the footage earlier.
But Mr Drew disputed this. "The video, they would have had it Friday night, they could have shown it to us Saturday morning," he said. "(That would have saved) us that little bit of anguish we had gone through.
"You've got that information ... the family would have appreciated seeing things sooner." The parents of Josh Ufer, one of two Australians trapped in the mine, refused to comment to reporters.
Family of the second Australian Willy Joynson, 49, are also waiting in New Zealand for news.
