Newly released video footage from inside the Pike River mine has revealed the extensive damage from the second blast on Wednesday, which extinguished all hope for the 29 trapped miners.
The company's chief executive, Peter Whittall, told a news conference on Friday that an Australian robot had reached nearly 1600 metres up the mine.
He says the damage done by the second blast was clear from debris in the area around the loader abandoned by survivor Russell Smith.
Beyond that, the robot reached a conveyor belt area that had been badly damaged.
Mr Whittall says the footage confirmed his belief that Wednesday's blast had been much more violent than last Friday's one.
He says the air in the mine remains very gassy and they're being cautious about drilling a second bore hole.
Police Minister defends force
Responding to criticisms of the police, Police Minister Judith Collins says she believes officers have been doing a fantastic job under extraordinarily difficult circumstances.
Ms Collins is also defending the man in charge of the operation, Superintendent Gary Knowles, against criticism, particularly that coming from foreign media.
She says she has received many messages of support for him.
Ms Collins also says that when she met with the miners' families on Friday they applauded when she mentioned Supt Knowles.