Northern Territory Sports Minister and Assistant Treasurer Nathan Barrett has resigned from Cabinet after sending videos of himself engaged in a sex act to a constituent.

Key points: Mr Barrett says he is "very disappointed" by his actions

Mr Barrett says he is "very disappointed" by his actions Says he was in a relationship with the woman for a short period

Says he was in a relationship with the woman for a short period NT Chief Adam Giles says Barrett 'had to go'

Mr Barrett has apologised for his actions, which he said involved a woman he was with for a short period.

"I endeavour to represent my community effectively and improve the lives of the people of Blain and the entire Northern Territory."

He admitted to being engaged in an "inappropriate relationship".

"While this is essentially a private matter that my wife and I have been working through for some time, I unreservedly apologise to my family, the people of my electorate of Blain, my parliamentary colleagues, the party, and the men and women in the Department of Sport and Recreation and Youth Affairs," he said.

'He had to go' says NT Chief

The resignation came after the NT News reported Mr Barrett had sent videos of himself engaged in a sex act to a constituent.

He apologised to the woman that he sent the videos to.

"I will now work to rebuild the trust of the people of Blain whilst I seek counselling," Mr Barrett said.

NT Chief Minister Adam Giles said he was horrified by events.

"To see what transpired in today's newspaper, to me, frankly, is not good enough ... it's not the behaviour of a person who wants to be a minister in the Northern Territory," he said on Saturday.

He said he would be taking over Mr Barrett's ministerial responsibilities until the NT's August 27 election and Mr Barrett "had to go" from Cabinet.

"This issue is a matter of what I would see as public interest, because it's crossing over those elements of what I would call harassment to young women," Mr Giles said.

Mr Giles would not comment on whether Mr Barrett should stay in politics and recontest the election.

"That's a matter for the party," Mr Giles said.

'Barrett should reconsider future in politics'

He said his Government had recently passed legislation to protect people from so-called sexting.

"Sexting is not a relationship issue. Sexting goes beyond that."

Mr Barrett was due to speak to media this morning about his actions but the conference was called off shortly before it was due to begin.

The announcement that he had resigned came less than an hour after the media conference was cancelled.

CLP Federal Member for Solomon Natasha Griggs said Mr Barrett should now reconsider his future in politics.

"I feel very sorry for his family but as politicians we have to make sure that our community has faith and believes that we wouldn't do the wrong thing," Ms Griggs said.