Denmark's Prince Henrik, who publicly vented his frustration at not being the social equal of his wife, Queen Margrethe, and refused to be buried with her, has died at the age of 83.

Key points: Prince Henrik was struck with an illness during a trip to Egypt

Prince Henrik was struck with an illness during a trip to Egypt He wanted to spend "his final time" at Fredensborg Castle

He wanted to spend "his final time" at Fredensborg Castle He was a passionate artist known for his love of wine and food

The Prince died "peacefully in his sleep" at Fredensborg Castle, a statement from the royal family said, adding "Her Majesty the Queen and the two sons were at his side".

The French-born prince, who was the father-in-law of Australian-born Crown Princess Mary, was diagnosed with a benign tumour two weeks ago.

He had been hospitalised following an illness that began during a private trip to Egypt.

Shortly before his death, he was transferred from a Copenhagen hospital back to the castle, north of the city, where he had wanted to spend "his final time".

Prince Henrik sparked controversy in August 2017 when he announced he did not wish to be buried next to the Queen, breaking a 459 years old tradition.

He said he was unhappy she had never acknowledged him as her equal.

Shortly after, the palace announced that Prince Henrik was suffering from dementia.

He formerly held the title of Prince Consort but renounced that title when he retired from his official duties in 2016.

He had often spoken of his frustration at being denied the title of king.

Traditionally in Denmark, while a princess becomes queen when her husband takes the throne, a man does not become king when the roles are reversed.

After a 2009 Danish referendum supported the equality of the sexes in the royal succession, Henrik remarked: "I hope that men will be as equal as girls," spurring further debate and briefly finding support in parliament in favour of allowing him the title of king.

But no law was ever passed.

When Prince Frederik becomes king, his Australian-born wife will be a queen. ( Reuters: Scanpix Denmark )

A passionate artist

Henrik lived his first five years in French Indochina.

He graduated from universities in Paris, learned Mandarin and Vietnamese and spent a year at the Hong Kong University from 1958-1959.

After his move to Denmark, Henrik, a keen pianist, was active in different organisations and wrote poetry, memoirs and books, including a coffee table book on French gastronomy in 1999.

Margrethe and Henrik also owned a chateau in southwestern France where they retreated every summer.

As a member of Denmark's royal family, he held honorary ranks of general in the Danish army and air force, and was an admiral in the navy.

Known for his love of wine and food, the Prince was also a passionate artist, producing several poems, sculptures and cooking books.

Born Henri Marie Jean Andre de Laborde de Monpezat in France in 1934, he married Margrethe in 1967.

Henrik has two sons with the queen, Crown Prince Frederik and Prince Joachim.

Reuters