Lock The Gate Alliance has apologised to Origin Energy and the Scientific Inquiry into Hydraulic Fracturing in the NT over allegations it made that the company had been involved in a "cover-up" of information.

Lock The Gate spokeswoman, Naomi Hogan, accused Origin Energy of omitting an important diagram of a well deformation, at Amungee Mungee Station near Daly Waters, from its initial submissions to the inquiry.

It also said the diagram showing the deformation had been submitted to the NT Government in February 2017 and accused both of providing the inquiry with "false and misleading information".

But the allegations were rejected by the inquiry's chair, Justice Rachel Pepper, as "scandalous".

Justice Rachel Pepper labelled the allegations "scandalous." ( ABC News: Jane Bardon )

In a letter from Sunday, Justice Pepper called on Ms Hogan to apologise.

"Given the scandalous nature of your allegations against Origin and the inquiry which have now been proven to be wholly incorrect, it remains a matter of considerable concern that no apology has been proffered by you, on behalf of Lock the Gate, to Origin or the inquiry," she said.

"Failure to do so has the very real effect of impugning the credibility of yourself and Lock the Gate."

In response to Justice Pepper, Ms Hogan said Lock The Gate "apologised unreservedly".

"We want to make it clear that in raising the issue we did not intend to impugn the integrity of the panel in anyway whatsoever," she said.

"We believed at the time it was a reasonable concern to raise based on the information before us.

"We appreciate the panel has now looked into the matter and concluded that the matter did not involve a cover-up and we sincerely apologise for any adverse impact the allegations had on the panel or Origin."

Justice Pepper accepted the apology and assumed the group had also apologised directly to Origin.

Origin Energy's capped Amungee NW-1 well now sits alone on a bare pad 50 kilometres east of Daly Waters. ( ABC Rural: Daniel Fitzgerald )

A spokesperson for Origin said the company welcomed Lock The Gate's letter and was "still awaiting a similar apology".

"This is a really important issue and we welcome a healthy debate," the company said in a statement.

"But it has to be based in truth and not driven by false information, which is what the inquiry witnessed last week and I think unfortunately what many in the community has heard in this whole process."

Lock The Gate has been contacted for comment.

