By Geraldine Coughlan
BBC News, The Hague
The Dutch government has stepped up measures against alleged Islamic extremists, amid calls for Queen Beatrix to unite the people.
Attacks on Christian and Muslim buildings have heightened tensions
It comes as ethnic tensions mounted after a siege in The Hague on Wednesday in which four police officers were hurt by a grenade and two suspects arrested.
The Dutch parliament has begun a debate over the murder of a film-maker last week by a suspected Muslim radical.
It set off a series of retaliatory attacks on Islamic and Christian sites.
The right-wing maverick politician Geert Wilders opened the debate by calling for radical mosques to be closed down and their imams to be deported.
He said there were about 100,000 radical Muslims in the Netherlands and that they should abide by Dutch democracy or leave the country.
Queen Beatrix has been urged to call for unity after anti-terror arrests
The government has announced new measures to combat violent extremism, including increasing security services and more money to protect people and buildings.
The government is also to consider stripping immigrants with dual nationality of their Dutch citizenship when they "act against the interests of the state".
There have been calls for Queen Beatrix to help calm tensions as attacks on mosques and churches have continued.
Ahead of the parliamentary debate, Justice Minister Piet Hein Donner announced new steps to make it easier to infiltrate terrorist networks.
He said the film-maker Theo Van Gogh's murder and the arrest this week of 13 terror suspects clearly showed more powers were needed to combat terrorism.