The father of Danish Queen Mary, Professor John Dalgleish Donaldson, has died at 84 years old.

The Danish royal house announced the passing of Prof Donaldson on Sunday, just weeks after King Frederik X and Queen Mary visited Australia.

'My heart is heavy, and my thoughts are grey. My beloved father has passed away,' Mary said in a statement.

'But I know that when the grief settles, the memories will brighten my day, and what will remain strongest is love and gratitude for everything he gave me and taught me.'

Denmark's royal house said Prof Donaldson's 'health has been declining over the past few years' and Mary visited him in late March.

The family will hold a private memorial service at a later date.

Prof Donaldson was a Professor of Applied Mathematics, born in Scotland on September 5, 1941.

He moved to Tasmania with his first wife, Henrietta Clark Horne, in November 1963.

The couple welcomed their daughter, Mary Elizabeth Donaldson, on February 5, 1972, in Hobart. 

The now-Queen of Denmark arrived in Australia alongside King Frederik X for a six-day state visit running from March 14 to March 19 - the couple's first official trip to the country since ascending the throne in January 2024.

At the end of that trip, Mary set aside time to visit her father. 

The retired mathematics professor had previously missed several significant family milestones due to his frailty - including Princess Isabella's confirmation and Mary's own coronation in Denmark.

Royal officials previously confirmed Mr Donaldson was unable to travel long distances because of his health.

Mary herself acknowledged the emotional reality at the time, saying: 'He is getting to be an elderly gentleman and he is not well enough to take the long trip back to Denmark for a confirmation, but he is with us in our hearts.'