A re-elected Labor government would sign a deal that would prevent uranium mining from ever taking place on a parcel of Aboriginal land that is to be incorporated into Kakadu National Park, Environment Minister Peter Garrett says.

Mr Garrett visited the marginal Darwin-based seat of Solomon on Tuesday, where he unveiled the Labor government's plan to expand Kakadu National Park to include a 1200-hectare parcel of land, situated to the east of Nourlangie Rock.

He said the decision had been made following a request by traditional owner, Jeffrey Lee.

Mr Lee, 39, the senior custodian of the land known as Koongarra, could have become a very rich man if he had allowed the French energy company, Areva, to activate its mineral lease to extract tonnes of uranium from the site.

"When you dig `em hole in that country, you're killing me," he told reporters.

"Money don't mean nothing to me.

"Country is very important to me."

Mr Garrett said that under a re-elected Labor government, Koongarra, which includes sacred burial sites and rock art, would forever be protected.

"This is an important decision by a traditional owner, a fantastic inclusion for Kakadu and a great benefit for the whole of Australia," he told reporters.

Although there is some criticism that the move would mean less employment opportunities and income for local Aborigines, Mr Garrett said world-heritage listed properties such as Kakadu generated about $12 billion worth of income for the Australian economy each year.

Mr Lee, who is a park ranger, said the growth of Kakadu National Park would result in an increase in visitors to the area.

"Traditional owners will be doing stuff on country," he said, adding that it was important to preserve land for future generations so non-indigenous Australians could learn about Aboriginal culture.

The Northern Land Council (NLC) welcomed the announcement, saying the Gjok clan had consistently stated their opposition to mining on Koongarra.

"I would like to acknowledge Mr Lee for his continuous advocacy for his people," NLC chief executive Kim Hill said.

The Australian Conservation Foundation (ACF) said the decision transcended politics.

"All politicians should support this important initiative," ACF executive director Don Henry said in a statement.

There have been moves by other Aboriginal traditional owners and environmental groups to prevent the expansion and development of other uranium-rich sites around Kakadu, such as Ranger and Jabiluka, because of concerns about inadequate environmental protection.