The Northern Territory Government plans to introduce legislation next month covering 27 parks and reserves to offset any future native title claims and to create certainty over their future use.

The Territory Government says it has reached agreement with traditional owners of all but one of the 28 parks involved.

The Minister for Indigenous Affairs, Clare Martin, says the traditional owners of Keep River National Park have rejected the offer.

Ms Martin says while agreement was needed by the end of 2004, Keep River will be granted an extension to see if it will come onboard.

"Unfortunately for the Keep River native title holders... we weren't able to reach agreement on the offer," she said.

"The offer for them has lapsed.

"Now we're not introducing the legislation into Parliament until February so it does give the land council and the Keep River native title holders an opportunity to review that decision."