The Federal Opposition's environment spokesman says the public will be watching closely to see if Environment Minister Peter Garrett approves an expansion of a Northern Territory uranium mine, given his longstanding opposition to uranium mining.

Environmentalists are calling for the Federal Government to reject a proposal to expand the Ranger Uranium Mine, which lies within the boundaries of Kakadu National Park.

Greg Hunt says Mr Garrett has spent much of his life opposing uranium mining but approved the expansion of the Beverley Uranium mine in South Australia last year.

Mr Garrett says the proposal to expand the Ranger Uranium Mine will be subject to a rigorous approval process.