Northern Territory Chief Minister Natasha Fyles has resigned amid revelations of an undisclosed share-holding in a manganese mine.

Fyles owns a small amount of shares in South32, the company behind a controversial mine in the remote community of Groote Eylandt.

Earlier this year, she said the NT government would not investigate air pollution levels or health impacts after community members raised concerns over potential manganese dust leaks.

The revelation of her shares, worth just over $2000, sparked calls from opposition leader Lia Finocchiaro for her resignation alongside rumours of a leadership change from inside NT Labor. Finocchiaro said Fyles’ actions represented a “profound betrayal of public trust”.

Fyles, 45, announced her resignation in a hastily arranged press conference on Tuesday afternoon, at which she took no questions. She said the shares were originally a gift from her grandmother while she was still a child.

“In recent years, BHP has undertaken various mergers and as a result I have been issued with small shareholdings in some other companies,” she said.

“I have always endeavoured to properly declare these holdings as they occurred, but upon further review of a personal interests, it became clear I did not declare one of these, a small shareholding in a company called South32 … That was an error, an error on my behalf and I do not have any excuse for it. It was not deliberate or intentional but it is unacceptable.”

Fyles, who took over as Chief Minister from Michael Gunner in May 2022, said she had “failed to meet the standards that are set for us”.

“I care too much about our government and what it has achieved, to allow my personal mistake to impact on our progress,” she said.

“There is no point dragging it out. I made a mistake. There is no excuse, I am owning up to it, I accept the consequences, that is the right thing to do.”

She will resign as Chief Minister and Health Minister on Thursday but will remain in parliament.

“I am excited to be a full-time local member and I commit to running for [her Darwin seat of] Nightcliff in the election next year,” she said.

Fyles has faced growing pressure in recent months, with this week’s revelations the latest in a string of shares scandals.

Last month, she was forced to divest shares in Woodside, after media and federal politicians called into question potential conflicts of interest, in particular the government’s large-scale expansion of the NT gas industry.

Last week, Fyles was referred to the NT’s Independent Commissioner Against Corruption by an independent backbencher over potential conflicts of interest.

-with AAP