Queen Margrethe II stepped down as monarch today after 52 years on the throne

King Frederik and Queen Mary kissed on the balcony of Christiansborg Palace today in their first historic appearance as monarchs, after months of "affair" rumours.

Queen Margrethe II, 83, formally abdicated after reigning for 52 years, after which she was the longest-running living monarch in Europe.

King Frederik, at first, made a solo appearance where he addressed the crowds in Danish.

After receiving cheers from the crowds, he was then joined by his wife, Queen Mary, followed by their four children.

Crown Prince Christian, 18, Princess Isabella, 16, and twins Prince Vincent and Princess Josephine, both 13, all looked proud of their parents on the balcony today.

In November, Frederik made headlines after a Spanish gossip magazine reported that the then-Crown Prince had an affair with a Mexican socialite.

The socialite, Genoveva Casanova, strenuously denied the claim that she had a romantic affair with Frederik.

Speaking to Hola!, Casanova "categorically" refuted any suggestion she was romantically involved with Frederik after they were photographed together in Madrid.

Meanwhile, the Danish royal palace refused to make any comment on the rumours.

Mary and Frederik put on a strong show of unity today after they kissed on the balcony of Christiansborg Palace.

Earlier today, Queen Margrethe II, Frederik and Mary made their way to Christiansborg Palace for the formal transfer of power.

After the abdication was signed, the former Queen returned to Amalienborg.

Her eldest son is now the King of Denmark, and his Australian-born wife is his Queen.

Mary, 51, looked gorgeous in a white dress today which was designed by Soeren Le Schmidt and sewn by Birgit Hallstein.

Hallstein was chosen to sew Mary's beautiful wedding gown from her 2004 wedding to King Frederik.