Princess Mary's twins join their dad for a run in the snow for special announcement

Crown Princess Mary's youngest children have joined their dad for a run through the snow to give an update to royal fans about a major event scheduled for later this year.

The Royal Run takes place annually across various locations in Denmark and is one of the most popular summer events, drawing crowds of 80,000 people.

But last year it was cancelled due to the coronavirus pandemic.

Crown Prince Frederik has shared a video featuring himself and his twins, Prince Vincent and Princess Josephine – who turned 10 in January – to confirm changes to the 2021 event.

They are seen sprinting and laughing, racing each other in the snow.

The 2021 Royal Run was due to be held in May but has been moved to September 21, because of COVID-19.

Both Crown Prince Frederik and Crown Princess Mary are due to participate in the run, as they have done in previous years.

The run will take place in Sønderborg, Aalborg, Odense and Copenhagen/Frederiksberg.

A new date for the event in Greenland is yet to be confirmed.

"It has been decided to postpone the Royal Run yet again until September 12, when we hope that it will again be possible to gather so many people," Crown Prince Frederik said.

"In the meantime, we must make sure to keep (our) body and soul going. Especially now in winter – it provides energy and physical well-being.

"So, I hope that many of you will use the time from now until September 12 on maintaining the enjoyment of exercise and running that Royal Run has already brought."

The Royal Run was the brainchild of Prince Frederik, developed ahead of his 50th birthday in May 2018.

It includes three levels – one mile (1.6 kilometres), five kilometres and 10 kilometres – and participants are welcome to walk, if they prefer.