Speaking after being honoured for services to Scottish tourism, she said she was aware that of erosion problems caused by the number of visitors “trampling around” the site, near Inverness.

The time-travel series of books and a hit TV adaptation follow the romantic adventures of Second World War nurse Claire Randall after she goes back in time to 18th century Scotland, where she falls for Jacobite warrior Jamie Fraser.

Gabaldon, who revealed she has almost finished the ninth novel in the series after starting work on it five years ago, spoke out months after it emerged a Clan Fraser memorial stone at Culloden, which has recorded a 66 per cent increased in visitors in the space of four years since the TV show began, had to be sealed off to allow turf repairs to be carried out.

Outlander author Diana Gabaldon was recognised for services to Scottish tourism at VisitScotland's Thistle Awards this week.

Gabaldon, who has sold 35 million Outlander books sine 1991, vowed to continue speaking against “real estate firms” planning housing developments near sites like Culloden, saying she had been “appalled” at the insensitive promotion of some projects.

• READ MORE: Outlander season 5: Sam Heughan promises fans they won’t be disappointedNew research published this week by tourism agency VisitScotland revealed that visits to sites used as locations in the Sony-Starz TV series had leapt up by nearly 600,000 since it went into production.

There has been a 44 per cent increase in visitors to the official Glencoe visitor centre, a 42 per cent rise recorded at Blackness, in East Lothian, and a 30 per cent hike in the number of people flocking to Linlithgow Palace.

The Isle of Skye and Glenfinnan, which have strong links with Bonnie Prince Charlie, have also seen huge increases in visitor numbers since the TV show started.

However the National Trust for Scotland has urged the Scottish Government to give sensitive sites across the country much greater protection in future amid claims "Scotland's heritage is too often being cast aside for long-term economic gain."

Historians and academics have also warned that growing numbers are having an adverse impact on sites like Culloden amid growing reports of Outlander fans taking selfies and having picnics at.

However Gabaldon said it was important for measures to be put in place to ensure that historic sites were protected from both growing visitor numbers and new housing developments in future.

• READ MORE: Sam Heughan: Outlander’s value for Scotland is ‘grossly underestimated’Gabaldon said: "I've been against building near the Culloden battlefield. I'm not a UK citizen, so I'm not allowed to sign petitions and thinks like that but I retweet campaigns and other movements.

"I was somewhat appalled that there was a development called Cairnfields. Do they even know what a cairn is and what they are building next to?

"I think there does have to be a great deal of protection for heritage sites and not just from commercial development - there is also the sheer friction of their popularity and the impact of people trampling around.

"The people at Culloden have not said anything to me directly but I've heard that they have been somewhat concerned that so many people have visited the Clan Fraser memorial stone they have worn away all of the grass around it.

"There is perhaps a need for more education at visitor centres to explain that this is a delicate environment and people should keep their visit as short and unobtrusive as possible."

Meanwhile Gabaldon has urged BBC Scotland to consider showing Outlander on its new channel - despite rumours they were put off by UK Government concerns that it was "anti-British."

The author said she hoped the show would eventually be seen by a mainstream television audience in the country where the show is made, in a converted warehouse in Cumbernauld, Lanarkshire.

New instalments of Outlander go out on the streaming service, while repeats are screened on Channel 4 spin-off More4.

Gabaldon said: "I've love Outlander to be shown on BBC Scotland. It would be great if they could do that.

"The BBC didn't take it the first time around. I don't see any reason why they wouldn't show it. We couldn't think of any reason to begin with.

"The rumour at the time Outlander came out was that (Prime Minister) David Cameron did not want the show shown because of the independence referendum because the show in anti-British. I don't know if there was anything to it. It didn't do the show any harm.

"I'd say to the BBC they should have a look at it. It would be great to have it on a mainstream channel. A lot of people in Scotland watch it on DVD. It's not a water-cooler show in the UK."

Outlander author Diana Gabaldon calls for greater protection of Scottish heritage sites