Communist Vietnam on Wednesday opened an international arts festival with a parade celebrating the country's forgotten royal heritage with pomp, elephants and hundreds of actors in costume.

Vietnam's Nguyen dynasty was decried as feudal and decadent after the communists' victory of 1975, but a generation later Vietnam is embracing its royal past as part of its ancient culture and as a tourist drawcard.

Artists and dance troops from 23 nations have come to Hue, the city on the Perfume River that prides itself on being Vietnam's cultural capital, for a nine-day festival that has been held here every two years since 2000.

In a sunrise procession starting at the world heritage-listed Citadel on Wednesday, 900 actors wearing the tunics of mandarins and high court officials took part in an elephant parade that recreated the ancient Nam Giao ritual.

"Oriental emperors considered themselves the sons of heaven and earth, and in this ritual they paid respect to their parents," said Huynh Thi Anh Van, a heritage expert with the Hue Monuments Conservation Centre.

"In the past, only high-ranking mandarins and royal family members were allowed inside the Citadel. The rituals were very secret. At the Hue Festival the people can explore and witness what royal life was like."

The moated Citadel, modelled on Beijing's Forbidden City and the former seat of the Nguyen emperors, saw heavy fighting during the Vietnam war's 1968 Tet Offensive, leaving many of its palaces, temples and gardens in ruins.

But on Tuesday night the arched roofs of its South Gate ? restored as part of the city's UNESCO World Heritage-listed complex ? served as a backdrop to a show that featured more benign explosions in the night sky.

"I tried to make a very poetic and elegant fireworks," said Hue Festival pyrotechnics designer Pierre-Alain Hubert, who choreographed Vietnamese women travelling in cyclo rickshaws and waving lotus flowers alight with flames.

Traditional dancers and singers from the host nation performed alongside groups from former colonial power France, the main foreign sponsor of the festival, as well as nations including China, Japan, South Korea and Belgium.

Looking back

One Hue native who came back for the festival was Duc Minh Bui, a California-based medical doctor who remembers fleeing during the final days of the Vietnam war, when much of the city lay in ruins.

"It was a very difficult time then," he recalled. "Everybody tried to leave and the street south to Danang was clogged with masses of people pushing carts and carrying children. It was a nightmare spectacle."

Today, Bui is happy to see peacetime Vietnam celebrate its royal era, which ended when Bao Dai, the last emperor of the Nguyen dynasty, abdicated in 1945.

"Hue is the spirit of Vietnam, and the festival helps preserve Vietnamese culture," he said. "We should adapt to new things but also remember the old ideas of the ancestors for the sake of our country and our culture."

To add to the royal glitz, Hue has just reopened another key site ? the An Dinh summer residence of the 12th and penultimate emperor Khai Dinh, who had a fondness for Versailles-style interior decor.

In the years after the war, when the palace sheltered refugees, the silk canvases deteriorated and the painted wallpapers and stucco ornaments were covered in lime coats, industrial paint and soot.

A German aid project has now uncovered and restored 1700 square metres of the ornate wall paintings, training a group of curators in the process.

"There isn't another building like this in Vietnam," enthused Andrea Teufel, chief restorer of the 300 000-euro project organised by the group German Conservation Restoration and Education Projects.

The festival's royal aspect is a sign of changing times for Vietnam, said Michael DiGregorio, programme officer for arts and culture at the US-based Ford Foundation, one of the festival's sponsors.

"Vietnam is now a player in a globalised economy in which it needs to present itself, and like any other country Vietnam wants to represent itself as having a long history and traditions and a civilised culture," he said.

"Traditions formerly criticised under a different kind of modernisation regime have been revived because they fit into the kind of globalised context where people relate to each other economically but also culturally."