Fylingdales is part of the "Star Wars" defence system

The Park Authority says the work needed to make it part of the US missile defence system dubbed "Son of Star Wars" does not require planning permission.

But assurances are being sought that the work is not the start of large-scale development at the early warning station.

And the authority has also asked that radiation from the base is monitored.

The decision has come as a disappointment to the Fylingdales Action Network which monitors developments at the site.

There is no evidence to suggest a health risk from RAF Fylingdales. MoD spokesman

Keith Mollison of the Action Network told BBC News Online: "The park is a National Park, held in trust for everyone.

"The park executive need to stand up for what they believe in, in terms of the park, instead of just standing by and letting the MoD do what they will.

"It's not being disloyal, or treasonable, it's promoting the integrity of the park."

The MoD says it has published a detailed Environmental and Land use Report on all aspects of the upgrade for planning authorities.

A spokesman said: "The report supports our conclusion that no formal planning consultation will be required for the work.

"There is no evidence to suggest a health risk from RAF Fylingdales. As the Environmental report makes clear the emissions from the radar are many times lower than the safe levels set by the National Radiological Protection Board.

"We have been very open with the North York Moors National Park Authority about the environmental and health impact of the radar and we have been keen to take account of concerns that local residents in the Fylingdales area have."