Willem-Alexander of the Netherlands has become the newest and youngest monarch in Europe. His mother Queen Beatrix has abdicated and handed over the throne to her son.

46-year-old Willem-Alexander is the first Dutch king since 1890 and also the first of a new wave of relatively youthful European monarchs.

Among those attending the ceremony in Amsterdam this morning were future kings and queens including Prince Charles of Britain.

It is thought that some 800,000 visitors are in the Dutch capital as 75-year-old Beatrix ends her reign of 33 years.

King Willem-Alexander & Queen Máxima

She signed the act of abdication at the Royal Palace just after 9am Irish time.

A stream of well-wishers poured into Dam Square in the city opposite the Palace early hoping to catch a glimpse of the now-King Willem-Alexander and his wife 41-year-old Queen Maxima.

Reports say Dam Square has nearly reached full capacity. The City of Amsterdam says that street market stands have been set up at various locations throughout the city.

"There is a pleasant atmosphere in the city and the festivities are beginning gradually. No notable incidents have been reported" it added.

Some people spent the night on the main square to ensure a good view of the royal balcony. Meanwhile people from across the Netherlands descended on the capital with many carrying Dutch flags.