Outlander star Sam Heughan believes Scotland has been “late” to capitalise on tourist interest generated by the hit show.

Dozens of filming locations used in the time-travelling drama - including the likes of Blackness and Doune Castles - have experienced a spike in visitor numbers following the soaring popularity of the show, with heritage bodies lauding the boost created by the “Outlander effect”.

However, Heughan, who plays lead Jamie Fraser told the Radio Times tourism bosses have failed to properly take advantage of the increase, citing a flood of ‘unofficial’ tour operators promising to ferry fans around the drama’s version of Scotland.

READ MORE: Outlander fans swarm Scottish heritage website to claim free tickets for filming locations

The show, based on the bestselling books by US author Diana Gabaldon, charts the adventures of former combat nurse Claire Fraser, played by Caitriona Balfe, who is transported back in time to 1743 where she meets Highland warrior Fraser.

Figures released last year put the rise in the number of people visiting the show’s filming locations at around 67 per cent.

Heughan said interest in the series from Scottish fans was increasing, but called on official tourism bodies to do more to exploit its popularity.

He said: “I think Scotland was actually kind of unaware of what’s been happening here for many years, I think we were under the radar a little bit. I think finally they’ve realised, I think Scottish tourism has obviously risen dramatically.”

HeraldScotland: Doune Castle near Stirling saw the largest surge in visitor numbers – more than tripling from 38,081 to 124,341Doune Castle near Stirling saw the largest surge in visitor numbers – more than tripling from 38,081 to 124,341

“Doune Castle, that played Castle Leoch, home to the Mackenzie clan in the show, was up 600 per cent in their tourism numbers, there’s so many now unofficial Outlander tours, there’s vast tourism here, so I think people are really realising and the Scottish government as well.”

He added: “But they’re maybe a little late to it, but it’s certainly doing great things for Scotland.”

Doune Castle near Stirling saw the largest surge in visitor numbers – more than tripling from 38,081 to 124,341 - according to a VisitScotland study.

Blackness Castle on the Firth of Forth, which features as Black Jack Randall’s headquarters, saw tourist visits increase from 15,197 the year before Outlander appeared on TV to more than 42,000 in 2017.

READ MORE: Outlander author wins award for tourist boost

Meanwhile, Glasgow Cathedral which stood in for a French hospital during filming, saw visitors rise from 233,172 to 389,101.

Author Gabaldon received an “International Contribution to Scottish Tourism” award from the national tourism body for her contribution to boosting visitor numbers across the country last year.

Series 5 of Outlander airs on the Starz network in the United States from Sunday 16th February, with each episode available on Amazon Prime in the UK the day after.