The government risks breaching an international agreement if it goes ahead with a controversial nuclear waste dump in a remote part of the Northern Territory, conservationists say, with Labor Senate candidate Nova Peris calling for the plan to be dropped.

Conservationists claim that the Muckaty dump, near Tennant Creek, would be in contravention of the UN declaration on the rights of indigenous peoples, which states that nations must "ensure that no storage or disposal of hazardous materials shall take place in the lands or territories of indigenous peoples without their free, prior and informed consent".

The basis of this consent is currently being challenged in the federal court, with a directions hearing set to take place in Melbourne on 26 August.

Opponents of the dump have waged a lengthy battle against the Northern Land Council, responsible for nominating the Muckaty site, which they claim didn't have the full consent of Indigenous communities before striking a $12m deal to choose the location eight years ago.

Gary Gray, the resources minister who recently visited the site, told Guardian Australia that the government would not push ahead with the Muckaty site until the case was resolved. Anti-dump campaigners have welcomed this, given that the case could take several years to conclude.

However, Gray added: "The government is not considering the viability of other sites. Under the National Radioactive Waste Management Act 2012, only volunteer nomination sites may be considered for a facility.

"Some traditional owners have expressed an interest in volunteering an additional site at Muckaty Station; however, at this stage no nomination has been received."

Gray ruled out the creation of an independent commission to nominate dumping sites, despite the UK and US having such arrangements, pointing out that Australia doesn't have "high level" nuclear waste. Most of Australia's nuclear waste is generated from the medical, scientific and defence industries.

Peris, who appears certain to enter the Senate representing the NT at the election, told Guardian Australia she would have considered crossing the floor over the nomination of Muckaty had she been in parliament at the time.

"I've spoken to the people involved and there's overwhelming support in the community for this to not go ahead," she said. "I've put my hand up to run in politics to represent people and this is something I feel very strongly about. The territory should be open for business, yes, but we need to consider environmental and social impacts, too."

The Coalition appears less conflicted over the Muckaty nomination, with Ian Macfarlane, the opposition resources spokesman, telling Guardian Australia: "The Coalition has supported the establishment of such a facility in the Northern Territory following extensive negotiations with traditional landholders.

"Low-level nuclear waste is a reality in Australia, largely as a result of medical treatment. It is currently being stored in unsuitable places, such as shipping containers in hospital car parks or building basements.

"The Coalition believes that proceeding with plans to build a nuclear waste facility in the Northern Territory will be the best way to safely and responsibly dispose of it."

Anti-dump activists, who include environmental groups and Aboriginal community leaders, claim that the Muckaty plan is unjust and unsafe.

"Minister Gray's statement is a welcome change in style, but what we want to see is a change in substance," said Dave Sweeney, nuclear-free campaign director at the Australian Conservation Foundation.

"We would want a clarification that he won't accept any nomination in the Muckaty area by the NLC, because any alternative will face the same opposition from the community.

"We need to take a step back and take an evidence-based approach and consult countries that have disposed of nuclear waste on how best to do it, rather than it being a departmental decision.

"It's completely unacceptable to impose a divide-and-rule regime on some of the poorest people in the country to take long-term industrial waste. That's not how a mature society behaves.

"There are also significant variables in the transport of waste. In Australia we routinely have road accidents and train derailments and this waste will have to move over extremely vast distances to Muckaty, so that's a huge issue."