A recovery team will re-enter Pike River Coal mine today after making good progress yesterday.
Yesterday was the first time they have gone back into the mine since a series of explosions starting on November 19 killed 29 men, trapping their bodies 2.5 kilometres underground.
Mines Rescue Service general manager Trevor Watts said the team would this morning review gas monitoring data which has come out from the mine overnight to ensure no oxygen has got into the mine and it was safe to re-enter.
"When our teams arrive on site they will continue the work that they very successfully completed yesterday," Mr Watts told Radio New Zealand.
"They will continue on with preparing the site for the temporary seal.. and they will also be moving more equipment into the mine," he said.
Statutory mine manager Steve Ellis told NZPA yesterday the three teams, each wearing breathing gear and working in two hour blocks, yesterday began setting up a new seal 168 metres in from the entrance.
"It went very well, the conditions were favourable this morning."
It took them a little longer to enter the mine than expected because "of the fantastic job of concreting the doors up".
Mr Ellis said it was hoped the pumping of a compound like expanding foam would start either late today or early tomorrow.
They would then withdraw from the mine and monitor it for a week or two.
Eventually a steel door would be installed in the seal and the plan was then to remove the old seal at the mine entrance, a shipping container embedded in concrete installed just after the explosions.
The miners' families have been warned the rescue mission would be difficult and could take up to two years.
Prime Minister John Key said the Government's view was when it was safe to enter the mine "then that would be a welcome thing".
"We understand the stress that those families have been suffering and the very strong desire they have for recovery of their loved ones.
"My view's always been we couldn't put at risk the lives of those going to undertake that recovery effort, but that's a matter for others to determine whether actually this is the appropriate time.
"Clearly they feel it is and therefore we ultimately and fully support them in doing that but I'm not in a position to judge when it's safe to enter a mine or not."
Greymouth mayor Tony Kokshoorn said yesterday the plan to re-enter the mine was a "real confidence booster" for Greymouth.
"This is a big step forward, we've been waiting now with the families for seven months and it's been a hard, hard seven months.
