Denmark's Queen Margrethe II has announced her surprise abdication in a new year TV address.

She will abdicate on 14 January, which will be 52 years to the day since she became queen.

"I will leave the throne to my son, Crown Prince Frederik," she announced.

The 83-year-old is the longest serving monarch in Danish history, taking the throne after the death of her father King Frederik IX in 1972.

She revealed the decision was made after a period of reflection following surgery on her back in early 2023.

"The surgery naturally gave rise to thinking about the future - whether the time had come to leave the responsibility to the next generation," she said.

"I have decided that now is the right time," she added, and offered her thanks to the Danish public for their support over the years.

Prime Minister Mette Frederiksen thanked the queen for her service.

"On behalf of the entire population, I would like to extend a heartfelt thank you to Her Majesty The Queen for her lifelong dedication and tireless efforts for the Kingdom," she said in a statement.

"Queen Margrethe is the epitome of Denmark and throughout the years has put words and feelings into who we are as a people and as a nation."

Unlike British royal tradition, there will be no formal crowning ceremony for Crown Prince Frederik, who is 55. Instead, the his ascension will be announced from Amalienborg Castle in Copenhagen on the day.

Queen Margrethe is a popular figure in Denmark, and many Danes had expected her to remain on the throne until her death.

During her time on the throne she continued to work as an artist and was well known for her love of the arts.

She also studied in the UK, spending time at Cambridge's Girton College and the London School of Economics.

Each year on New Year's Eve, she delivers a speech broadcast on television.

This year, aside from the announcement, she also spoke of the wars in the Middle East and Ukraine, as well as the importance of addressing climate change.

Facing similar challenges of modern society as other royal families across Europe, the Danish royal family has decided to slim down its number of royals.

This led to a very public rift last year after Crown Prince Frederik's younger brother Prince Joachim's children were stripped of their royal titles.