Thailand's Queen Mother Sirikit, who brought glamour and elegance to a postwar revival in the country's monarchy and who, in later years, would occasionally wade into politics, has died aged 93, the Thai Royal Household bureau said on Saturday.

Her husband, King Bhumibol Adulyadej, was Thailand's longest-reigning monarch, with 70 years on the throne since 1946.

She was at his side for much of that, winning over hearts at home with their charity work.

Sirikit had been out of the public eye since a stroke in 2012.

When they travelled abroad, she also charmed the world's media with her beauty and fashion sense.

During a 1960 visit to the United States that included a state dinner at the White House, Time magazine called her "svelte" and "archfeminist".

The French daily L'Aurore described her as "ravishing".

Born in 1932, the year Thailand transitioned to a constitutional monarchy from an absolute monarchy, Sirikit Kitiyakara was the daughter of Thailand's ambassador to France and led a life of wealth and privilege.

While studying music and language in Paris she met Bhumibol, who had spent parts of his childhood in Switzerland.

"It was hate at first sight," she said in a BBC documentary, noting that he had arrived late to their first meeting. "Then it was love."

The couple spent time together in Paris and were engaged in 1949.

They married in Thailand a year later when she was 17.

Always stylish, Sirikit collaborated with French couturier Pierre Balmain on eye-catching outfits made from Thai silk.

By supporting the preservation of traditional weaving practices, she is credited with helping revitalise Thailand's silk industry.

For more than four decades, she frequently travelled with the king to remote villages, promoting development projects for the rural poor – their activities televised nightly on the country's Royal Bulletin.

She was briefly regent in 1956, when her husband spent two weeks in a temple, studying to become a Buddhist monk in a rite of passage common in Thailand.

In 1976, her birthday, August 12, became Mother's Day and a national holiday in Thailand.

Her only son, now King Maha Vajiralongkorn, also known as Rama X, succeeded Bhumibol after his death in 2016 and upon his coronation in 2019, Sirikit's formal title became the Queen Mother.

Officially, the monarchy is above politics in Thailand, whose modern history has been dominated by coups and unstable governments.

On occasion, though, the royals including Sirikit have either intervened or taken actions seen as political.

In 1998, she used her birthday address to urge Thais to unite behind the then prime minister, Chuan Leekpai, dealing a crippling blow to an opposition plan to hold a no-confidence debate in the hope of forcing a new election.

Later, she became associated with a political movement, the royalist People's Alliance for Democracy, whose protests brought down governments led by or allied to Thaksin Shinawatra, a populist former telecoms tycoon.

For many Thais, she will be remembered for her charitable work and a symbol of maternal virtue.

Her death will be treated with reverence in a country where any criticism is held at bay by strictly enforced lese-majeste laws, which prescribe potential prison sentences for insulting royals, even those who are dead.

She is survived as well by three daughters. (Reuters)