Amsterdam  - Queen Beatrix and other Dutch royals are to participate as planned in Monday night's annual World War II memorial despite the failed car-ramming attack on their open-top bus three days ago, Dutch television reported Sunday.

The ceremony in central Amsterdam will mark the queen's first public appearance since Thursday's attack on the royal family when a 38-year-old Dutch man drove his car into a crowd watching a royal procession. He intended to hit the royal bus but instead killed seven bystanders and injured 12.

The attacker died on Friday. Named in media reports as Karst Tates, he confirmed to police before he died that he had intended to attack the royal family.

Festivities planned for the May 5 Liberation Day will take place as planned, officials said, though some activities have been altered and given a more solemn character.

The queen will participate as will her son Crown Prince Willem- Alexander and his wife Maxima. The Amsterdam municipality said it might take extra security measures to protect the royal family on May 4 and 5.

Meanwhile Dutch television reported the Belgian authorities are taking extra precautionary measures to protect the Belgian royal house during its next public appearance at an annual parade scheduled for July 20.

The reports said Belgian authorities feared the Dutch incident might give people the idea the Belgian royals would be an "easy target."

On Saturday Queen Beatrix, the crown prince and his wife, and the queen's sister Princess Margriet and her husband Pieter van Vollenhoven visited the eight people still hospitalized after sustaining injuries in Thursday's attack.

Thursday was a national public holiday in the Netherlands, and the 71-year-old queen, accompanied by other royals, was travelling through the town of Apeldoorn, 90 kilometres east of Amsterdam, in an open top bus when the attack occurred. (dpa)