Danish Crown Prince Frederik (R) and his wife Crown Princess Mary carry their twins as they leave the church with their son Prince Christian (L) after the Christening ceremony of the royal twins at Holmens Church in Copenhagen April 14, 2011. [Photo/Agencies]

COPENHAGEN - Denmark's royal twins, the youngest members of the country's 1,000 year-old monarchy, were christened in Copenhagen, the Danish capital, on Thursday.

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The three-month old twins, a boy and girl, are the children of Crown Prince Frederik, next in line to the Danish throne, and his Tasmanian-born wife Crown Princess Mary.

They were named Vincent Frederik Minik Alexander and Josephine Sophia Ivalo Mathilda, at an elegant ceremony in Copenhagen's 16th-century Holmens Church, on Thursday afternoon.

Born on Jan 8, 2011, the twins are separated in age by a gap of just 26 minutes, with Vincent being the elder of the two.

The giving of four names to each child has become a tradition in the Danish monarchy in recent generations.

Following royal tradition, every other Danish king has been named either Frederik or Christian. The little princess also bears the Greenlandic name  "Ivalo" , while  "Mathilda"  is a nod to her part-Australian parentage.

They are fourth and fifth in line to succeed the Danish throne, behind their father Crown Prince Frederik and older siblings Prince Christian, 5, and Princess Isabella, 3.

In the lead-up to the ceremony, several hundred people lined the streets outside the church, and stood on rooftops of adjoining buildings, waving Danish and Australian national flags, the latter in acknowledgment of the Crown Princess' roots.

The baptism was graced by Queen Margrethe of Denmark, her husband Prince Consort Henrik, and some 300 invited guests, including Crown Princess Mary's family from Australia, nobles from Greece and Germany, and Danish business tycoons, politicians and entertainers.

However, royals from neighboring monarchies such as Sweden, the Netherlands and Norway were unable to attend.

Several members of the Danish royal family, including Queen Margrethe, have previously also been baptized in Holmens Church. In keeping with Danish custom, the twins' names were revealed to the public for the first time at the baptism.

Denmark has one of the world's oldest surviving monarchies, with the present royal family being direct descendents of the royal house of Glucksborg, which acceded the throne in 1863.

The monarchy plays no role in the country's political affairs and is widely accepted by Danes.