Crown Prince Frederik and Crown Princess Mary of Denmark have come under fire after revealing they have made money from a private Swiss ski lodge they have secretly owned for 10 years.

The royal couple caused consternation in their home country's parliament last week when Crown Prince Frederik announced they would be spending their 12-week stay in Switzerland at their personal villa.

He went on to explain that they have owned the property in Verbier, one of the world's most exclusive ski resorts popular among the British royals, for a decade and rent it out when they're not using it.

The Danish royal family lives on a public allowance that is only allowed to be spent on foreign assets with the approval of lawmakers.

Crown Prince Frederik and Crown Princess Mary of Denmark, pictured with their children Prince Christian, Princess Isabella, Prince Vincent and Princess Josephine, have come under fire after revealing they have made money from a private Swiss ski lodge they have secretly owned for 10 years

At the beginning of January, the couple's children Prince Christian, 14, Princess Isabella, 12, Prince Vincent, nine, and Princess Josephine, also nine, began spring term at the Lemania-Verbier International School in Switzerland.

The children usually attend the Tranegård School in Gentofte, Denmark, but are attending the boarding school for three months in Bagnes, Switzerland to give them a more international experience.

Princess Mary is staying with them while they are in school, and Prince Frederik will travel between there and Denmark for his official duties.

When it emerged they'll be staying at their privately owned lodge, the Danish far-left parliamentarian party Enhedslisten hit out at the couple for keeping the fact they own such a home quiet.

At the beginning of January, the couple's children began spring term at the Lemania-Verbier International School in Switzerland. Pictured: the family on January 6 in Switzerland

Member of Parliament Mai Villadsen told Danish media: 'I was very surprised when I found out that the family does not just have such a house, they have had such a house for 10 years, without any ordinary Danes knowing about it.

'We are the ones who pay the money so we must know about the house.'

The Royal House initially refused to comment on the matter, claiming it considers the purchase of the property a 'private matter' - to which Ms Villadsen retorted: 'I find it very difficult to see that a royal estate can be a private matter. To my knowledge, the appanage has just increased.'

It has since emerged that the couple have also made money on the property, prompting outrage among Danes, reports Royal Central.

In response, the Royal Court issued an official statement stating that Crown Prince Frederik and Crown Princess Mary will no longer accept revenue on the ski lodge by renting it when they aren't using it, due to concerns over safety and privacy.

The Royal House initially refused to comment on the matter, claiming it considers the purchase of the property a 'private matter'. Pictured: Crown Prince Frederik and Crown Princess Mary at Queen Margrethe of Denmark's New Year reception for officers from the Armed Forces and the Emergency Management Agency on January 3

It insisted that everything to do with the house is paid for by the royal couple's private funds.

Lene Balleby, communications manager for the Danish Royal Family, told Danish media: 'Now it is no longer an anonymous property, so the conditions for rent are no longer the same.

'In addition, for the Crown Prince Couple, this makes a difference compared to the possibility of having some privacy.

Verbier is one of the world's most exclusive ski resorts and is popular among the British royals, including the Duke and Duchess of Cambridge and the Duke and Duchess of York

'In addition to that, there is also a safety aspect.'

Homes in the lavish Verbier resort can cost up to £1.5million. According to Danish magazine Billed-Bladet, the Crown Prince and Princess' property is a 'traditional Swiss wooden chalet with a nice, large terrace, located in a child-friendly neighbourhood and within walking distance of the children's school'.

While their secret residence drew criticism from one party within the Danish political sphere, Conservative member of parliament Birgitte Bergman said she can't see 'anything wrong' with the couple owning the Swiss home.

Homes in the lavish Verbier resort can cost up to £1.5million. According to Danish magazine Billed-Bladet, the Crown Prince and Princess' property is a 'traditional Swiss wooden chalet with a nice, large terrace, located in a child-friendly neighbourhood and within walking distance of the children's school'. Pictured: stock image of Swiss chalets in Verbier

'My party support the royal family 100 per cent and the dispositions they now make, as long as it is within the law,' she said.

'We cannot see anything wrong with that at all. This is also to be regarded as an old case. This happened 10 years ago and has no relevance today.'

The annual grant received by the Danish royal family is funded through taxes in the country and set by parliament.

Queen Margrethe II will receive 87.6 million kroner (£7,504,462) in 2020 and the crown prince and his family will receive 21.6 million kroner (£2,459,400).