Greens senator Lidia Thorpe is staring down a censure motion in the upper house, and an internal review, after she failed to disclose a relationship with a former bikie boss.

One Nation leader Pauline Hanson said she will move the censure motion when the Senate sits next week, labelling Senator Thorpe unfit to serve in parliament.

It was revealed on Thursday the Victorian senator failed to disclose a relationship with Dean Martin, the ex-president of the Rebels outlaw motorcycle gang, while she was sitting on a powerful parliamentary committee.

The ABC reported Senator Thorpe was in a relationship with Mr Martin in 2021 while serving on the law enforcement committee, which may have received confidential briefings about bikie gangs at the time.

Committee chair Helen Polley said a review was underway to examine whether Senator Thorpe had been briefed on sensitive information about bikie gangs during the course of her relationship.

“There’s been a breach of trust, and we want to check the facts,” the Labor senator said.

“She has shown such poor judgment, declaring a conflict of interest is Senate 101 … this feeds into the discourse that politicians are in it for themselves as the Albanese government is trying to restore that public faith in the integrity of politics.”

Senator Polley said the committee will be advised of any breach next Tuesday, and members would be reminded of their duty to keep confidences.

“With Senator Thorpe’s contempt for the Senate with the swearing-in ceremony and now the breach of trust in failing to advise of a conflict of interest, she should consider if it’s the right place for her,” she said.

While it is not known whether the censure motion will pass, Senator Hanson said the failure to disclose the relationship was a conflict of interest.

“The Greens demand integrity and principle from everyone except themselves,” she said in a statement.

“If Senator Thorpe had principles she would resign from the Senate. If Greens leader Adam Bandt had integrity he would kick her out of his party.”

The One Nation leader said she was exploring other sanctions or measures that parliament could take against Senator Thorpe following the revelations.

Following news of the relationship, Greens leader Adam Bandt asked for her resignation as the party’s deputy leader in the Senate. She complied.

But he said the lack of disclosure about the relationship represented a lack of judgment from the Victorian senator.

Senator Thorpe said she had accepted the mistakes she had made.

“I … have not exercised good judgment,” she said in a statement.

Education Minister Jason Clare said the relationship was a clear conflict of interest.

“You can’t be on an inquiry investigating outlaw motorcycle gangs and be in a relationship with an [ex-]outlaw motorcycle gang member, a bikie,” he told Seven’s Sunrise program on Friday.

“It seems to me just to be a no-brainer here that there is a massive conflict of interest.”

Senior Labor frontbencher Tanya Plibersek said Senator Thorpe could “date whoever she likes but it is a conflict”.

“I would say that the leader of the Greens should actually be explaining why it seems that people alerted his office to this conflict and no further action was taken,” shes aid.

“I think it’s really up to Adam Bandt to explain why that’s occurred.”

Senator Thorpe told the ABC she met Mr Martin “through Blak activism and briefly dated in early 2021”.

“We remain friends and have collaborated on our shared interests advocating for the rights of First Nations peoples,” she said.

Mr Martin has no criminal convictions, and there is no suggestion Senator Thorpe passed on any confidential information.

But Opposition Leader Peter Dutton said Senator Thorpe was unfit to sit in the parliament.

“Clearly she should resign, I think [Greens leader] Adam Bandt should do that. You can’t receive briefings in the day and hang out in nice circumstances with the bikies. It doesn’t add up,” he told the Nine Network.

“It should be the first order of business for any corruption commission to look into that and probe into what might be leaked.”

-with AAP