The Australian Conservation Foundation (ACF) says a uranium scare in Kakadu National Park yesterday shows the Ranger uranium mine should not be expanded.

Energy Resources Australia says a truck carrying uranium oxide through Kakadu became bogged when it pulled over to let another wide load pass by.

The road was blocked for three hours while sealed containers of uranium oxide were transferred to another truck.

The ACF's nuclear campaigner, Dave Sweeney, says he is relieved the incident was not more serious.

He says Ranger has a poor environmental track record.

"It certainly should be cause for concern. It should be cause for reflection. It should be an absolute warning about the plans by mining company Energy Resources Australia to expand Ranger," he said.

"This should be a red light for the expansion of Yellowcake in Kakadu. We should be putting the brakes, not just on the trucks coming out of Ranger but on the plans to expand Ranger."

Steve Thibeault, from Energy Resources Australia, says no uranium was spilled and the operation was a success.

"In this case we allocate the proper people to help us to evaluate contingency in different situations," he said.

"But more importantly we deploy people on site - operational people - to make sure they evaluate the site and make sure everything is OK.

"There was no environmental damage. There was no harm.

"During all the operation the safety of the employee, the contractors and the public, but most importantly the environment, was there."