Denmark’s royal family has united behind King Frederik X as he made his first appearance before the country’s MPs in parliament on day one as monarch.

Frederik was proclaimed King on Sunday (local time) by Prime Minister Mette Frederiksen in front of 174,000 cheering people who had converged on the capital in close to freezing temperatures.

The meeting in parliament on Monday (local time) to celebrate the succession of the throne was his first official task and he was flanked by his wife Queen Mary, mother Margrethe, brother Prince Joachim and eldest son Crown Prince Christian.

Frederik, 55, and Australian-born Mary, 51, arrived at the Folketing in a royal limousine and were greeted by speaker of parliament Søren Gade and senior MPs.

Queen Mary and King Frederik X arrive at the Danish Parliament. Photo: Getty

His mother Margrethe stood at the top of the stairs to the Christiansborg Palace and saw her son and daughter-in-law arrive.

Inside, the Danish family sat on the royal balcony overlooking the 179-member Folketinget assembly.

Frederik was smiling as he sat on the first row next to Mary and 18-year-old Crown Prince Christian.

Margrethe sat behind them.

Frederik’s brother Joachim, who had a public falling out with his mother when his four children lost their royal titles in 2022, sat next to Margrethe. He was earlier warmly greeted with a hug from the King.

Joachim flew to Denmark from his home in Washington, US, without his wife Princess Marie and youngest children, for the King’s accession but did not appear on the palace balcony after the ceremony.

Media have also speculated about a feud between Joachim and Frederik to rival that between Britain’s princes William and Harry.

King Frederik is supported by wife Queen Mary (left) and (behind) brother Prince Joachim and mother Margrethe. Photo: Getty

King Frederik is receiving the full support from prime minister Mette Frederiksen, whose party has grappled with how to relate to the monarchy.

Denmark has a constitutional monarchy, which means that the monarch as head of state must sign laws before they come into force but the formal power remains with government and the elected parliament.

The new king and queen take the throne at a time of huge public support for the monarchy in the country of nearly six million.

“Our amazing royal family is doing so well that we may take the monarchy for granted. It is not a given, it stands and falls with the people who take responsibility. And it rests on a mutual contract between monarchy and democracy,” Frederiksen said in a speech in parliament.

In a separate speech on January 1, Frederiksen said she had not always supported the monarchy but had declared herself a royalist due to the work Queen Margrethe had done to unite Denmark.

The royals sit above the Danish parliament. Photo: Getty

Frederiksen’s Social Democratic party has for a century refused to take decorations from royals but reversed this policy after Margrethe’s New Year’s Eve announcement of her abdication. It is now up to members if they wish to receive orders.

“The role of a king in a modern democratic society is a difficult balancing act in itself. Add to this the challenges we face in Denmark and in the world around us,” Frederiksen said.

“We very much need our king to unite Denmark.”

King Frederik addressed the crowds in a speech on Sunday but did not speak in parliament on Monday. It is tradition that the monarch does not speak directly to MPs, so Frederiksen read his speech.

The King referred to himself as “we”, using what is known as the majestic plural.

“We begin our responsible work as Denmark’s King in the belief that the Danish parliament will meet us in joint work for the good of the kingdom,” Frederik said through the prime minister.

Speaker Søren Gade said to Frederik that “I have great confidence that he will be an excellent king for us all. And by his side has an excellent queen.”

Gade greeted Frederik with “Long live His Majesty King Frederik X” when the King presented himself.

The assembled MPs responded unanimously with “Hurrah!” repeated nine times.

Danish radio’s girls’ choir then sang for the royal family.

-with AAP