The iconic "fake Uluru" roadhouse on the Pacific Highway north of Newcastle has been engulfed in a fierce blaze and destroyed.

Fire ripped through The Rock Roadhouse near Hawks Nest on the mid-north coast and the big (little) Ayers Rock — a famous site visited on many road trips — is now no more.

Inspector Ben Shepherd from the NSW Rural Fire Service said 18 crews were fighting the fire and ensuring it did not spread to nearby petrol bowsers.

The 1/40 Uluru replica was built for Leyland Brothers World, a 1990s theme park with amusement rides, the roadhouse and a bush camp.

It is not yet known what caused the fire. ( ABC News )

The park ended up sending the brothers broke and was sold in 1992.

"It is a local landmark and it is well known by many who travel that route, but unfortunately the structure has been completely destroyed by fire," Mr Shepherd said.

Mal Leyland said he was devastated that his dream was gone.

"I put it behind me many years ago when we lost it all to the banks, and you think it's dead and buried back in the memory somewhere 20-odd years ago, but nah it's not the case," he said.

"All of our money went down the gurgler when we lost it, so I had a strong emotional attachment and I feel quite devastated even though we had no connection with it now."

In recent years the building was used as a service station and the broader site hosted up to 45,000 school students a year on bush camping excursions

Mr Leyland said he had been told that the Uluru replica was in the process of being sold and the new owner had expressed interest in restoring the building to its former glory.

"He wanted to know if I could get involved in the process of restoring it to what it was a reopen it and then suddenly it was on the news, it was just shocking," he said.

"To see it back to what it was would have been a nice tribute."

The Uluru replica was built for the 1990 theme park Leylands Brothers World. ( Supplied: Wiki )

Employees escaped and there have been no reported injuries but it is not yet known how the blaze started.

The Great Aussie Bush Camp, a student education centre which was part of Leyland Brothers World but still operates today, was evacuated as a precaution.

Officers from Port Stephens-Hunter Police District have commenced investigations and are urging anyone with information to call Crime Stoppers on 1800 333 000.

Aerial shot of the roadhouse, petrol station and neighbouring bush camp. ( Youtube: Fabian Norrie )

This morning hundreds of locals and passers-by on the Pacific Highway stopped to take photos of the smouldering structure.

"It's kind of sad, it was something different to look at on the way down, it wasn't pretty but it was just always part of the landscape," Heather Cantwell, from Kempsey, said.

"I drive past this icon twice a day and I'm just absolutely devastated, it's going to be sorely missed," Kath Henry, from Karuah, said.