A ventilation shaft is now sealed and families of the victims have been told recovery teams will try to access the main tunnel by mid-June, according to a report by www.3news.co.nz.

Rescuers started the arduous task of re-entering the mine last October.

Family lawyer Colin Smith says it is a huge relief for many.

“This is another step in a positive direction, in terms of the goal of the families to ultimately re-enter the mine and recover their men,” he told 3news.

The New Zealand government is spending $NZ7.2 million on the tunnel re-entry and exploration project.

Earlier this year, unfavourable weather delayed efforts to plug the ventilation shaft of the explosion-prone Pike River Coal mine.

State-owned Solid bought the assets of the former Pike River Coal business in July 2012.

Solid said the weather over summer reduced the available days for the helicopter-dependent work, although preparation for the next stage of drilling boreholes for surveillance and gas drainage was well advanced.

While Solid does not yet plan to re-enter the buried mine workings, the re-entry project aims to inertise and explore the drift access tunnel down to where it is cut off by a rockfall some 2.3km in.

NZ Defence Force personnel assisted the project’s initial phases in October.