Amsterdam  - Members of the Dutch public applauded the country's monarch, Queen Beatrix, on Monday as she arrived at a World War II memorial service, days after an attacker had ploughed into a royal event in his car killing six.

Queen Beatrix arrived with Crown Prince Willem-Alexander and his wife Princess Maxima at the Nieuwe Kerk in Amsterdam, ahead of a national WWII ceremony which commemorates the country's war dead.

Officials said that security measures had been stepped up at the site, and that snipers were in position on rooftops overlooking Dam Square, where the ceremony was to take place.

On Thursday, a 38-year-old male drove his car into onlookers at the Queen's Day parade in the town of Apeldoorn, killing six and injuring 12. The Queen and other royal family members were not injured.

The man, who had reportedly intended to hit the royal vehicle at the event, died of his injuries on Friday.

Dutch police were empowered to conduct body searches on all civilians near the memorial site.

Earlier on Monday the city of Amsterdam confirmed it has also stepped up security measures ahead of Liberation Day events on Tuesday.

Queen Beatrix is due to attend a Liberation Day open-air concern near the Amstel river.

Beatrix's youngest son, Prince Constantijn, said that despite Thursday's attack, he supports the "open and informal character" of Queen's Day, on which the royals traditionally mingle with the public. (dpa)