The chances of a recovery team finding human remains have gone from unlikely to possible in a critical area of the Pike River Mine.
The Pike River Recovery Agency (PRRA) is giving a briefing in Christchurch this afternoon after reaching a point called the pit bottom in stone area.
The crucial zone is about 300m from the roof rockfall face.
The PRRA operation, which went back underground in May last year, is looking to see whether it can recover the 29 men killed during the November 19, 2010 disaster.
PRRA chief executive Dave Gawn says it is now possible that evidence of the miners could be found.
He says they're more optimistic because they're learning more about the blast, including its direction and effect on a confined space.
The miners' last known location was beyond the roof fall.
The re-entry mission's progress has been slow and held up with unexpected delays.
Earlier this year, Pike River Recovery Minister Andrew Little approved a further $10.8m funding to complete the project - as well as a $4.2m contingency – meaning the total operation could end up costing $51m. Its original budget was $23m.