After being received with military honours at the Romanian capital Bucharest, Britain's Charles III on Saturday visits Transylvania -- a region the king has said is in his "blood" as a descendant of Vlad the Impaler.

The king has frequently praised the charms of picturesque Transylvania in central Romania, where he has bought several traditional houses and set up a heritage foundation.

A long-time environmental advocate with a passion for nature, Charles has called Transylvania "literally the last unspoilt, untouched area".

As part of his first overseas visit since he was crowned king on May 6, Charles is headed to the village of Valea Zalanului -- some 100 kilometres (60 miles) away from the hamlet of Viscri, where he is expected to wrap up his trip on Tuesday.

As prince, King Charles first visited Viscri a quarter of a century ago, in 1998.

Dan Spataru from the local mayor's office said his return to the region was being welcomed as an "emotional gesture".

But in contrast to earlier visits, his trip as a newly crowned king will take on a "more formal, official" nature amid heightened security.

"We are sorry because the atmosphere was more relaxed before. Now it's a little stiffer," Spataru said of the tightened security protocol in place.

"Until 10 years ago Charles would walk around, go inside the villagers' courtyards, discover, without someone protecting him," said local guesthouse-owner Alexandru Toader.

"Now he can no longer do that because every time he comes it is highly publicised," he added.

The 37-year-old said in the past few weeks, authorities have even questioned him about the guests he was about to receive as part of security protocols.

- 'Soul connection' -

Charles bought his first house in Viscri in 2016, attracted by the region's dirt tracks, horse-drawn carriages and brightly-coloured houses nestled in green hills.

Initially intended as an occasional princely residence, it was later transformed into a museum dedicated to botany -- another of the new king's lifelong passions.

In Bucharest the royal environmentalist praised Romania for still being "home to many species of flora and fauna that have disappeared or are threatened elsewhere in Europe and the world."

Under Charles' sponsorship, the Mihai Eminescu Trust foundation has renovated several properties in Transylvania with traditional methods and materials to preserve the heritage.

Caroline Fernolend, president of the Mihai Eminescu Trust, told AFP that about 200 locals are expected to welcome Charles at the UNESCO-listed fortified church on Tuesday.

"It will be a unique moment to receive a king in our community," she said, grateful that Charles honours the work done "all these years".

Fernolend says there is no need to spruce up the village in anticipation of the king's visit.

"We won't prettify anything, the beauty is already there," she said, adding that the value of Viscri lies in its "people and the existing heritage."

At the reception in Bucharest on Friday, Charles said he has "always felt rather at home in Romania" in a reference to his links to infamous Vlad the Impaler through his great-grandmother Queen Mary.

According to Spataru, the king has always had a particular "soul connection" with Transylvania.

"When he comes here, he unwinds, he smiles more -- he is no longer the official, rigorous man," he said.