Lightning Ridge's new Australian Opal Centre (AOC) will have to wait a little longer after the museum's board opted to pause construction.

The two-story building in the area's opal fields is "80 per cent" complete, according to board chair Raymond Griffin, but he says "some cost headwinds along the way" have forced them to hit the brakes until they can meet a "sizeable" funding shortfall.

Construction has been paused since late May.

The non-profit organisation held off making a public announcement while it worked through a range of 'commercial in-confidence' aspects of the project.

Mr Griffin said they are now in a position to brief their founders, donors and members along with the general public in relation to the construction pause.

"The difficulty is with a remote location and an environment since COVID where there's been cost escalations seemingly ad nauseam," Mr Griffin said.

"We've just been very strategically careful to make sure that we've got all our funding lined up again.

"There's just been unforeseen costs, which we've worked together with our builder to work our way through.

"We are 100 per cent focused on getting this resolved, but it may take longer than we would like."

A 1:200 scale model of the Australian Opal Centre. [IMAGE: Penelope Clay]

Mr Griffin said he could not provide the precise shortfall.

The project received a $1 million boost in the NSW government budget this year, which Mr Griffin said is "extremely helpful" as they probe extra funding options.

He said the building's roof is largely complete, although they still need to install the ventilation system.

They also need to build an indoor walkway that will zigzag to the ground floor, as well as gabion walls along an outside walkway that descends to an underground entrance.

 The museum was designed by Australian architects Glenn Murcutt and Wendy Lewin, and is panned as a future hub for opal-related education and international tourism.

"We've had a number of estimates from the builder and along the way hurdles have come in front of them and in front of the whole project, which has meant that those estimates of completion have had to be pushed out," Mr Griffin said.

"It's a massively challenging project with a very large budget. It was always going to be difficult and, true to form, it's been difficult right to the end.

"It's not something that's insurmountable. You've just got to deal with it."

The Australian government approved almost $10.5 million for the project in March 2019, with another $7.5 million from the NSW government and $2 million from Walgett Shire Council.

The pause came not long after the museum's director Michelle Smith announced her resignation from the role on social media on 29 May.

The organisation hasn't yet begun advertising for a replacement, although the current museum in the Lightning Ridge township remains open.