Several leading Dutch politicians have been threatened with death since the killing of a controversial filmmaker earlier this week.
The De Telegraafnewspaper said those threatened included Ms Ayaan Hirsi Ali, a Somali refugee who is a prominent member of the VVD liberals, right-wing politician Mr Geert Wilders, Immigration Minister Rita Verdonk and Amsterdam Mayor Job Cohen.
Filmmaker Theo van Gogh was repeatedly stabbed after being shot as he cycled to work in Amsterdam on Tuesday. His throat was slit and a five-page letter suggesting a "radical Islamic" motive was pinned to his body with a knife.
A 26-year-old with dual Moroccan and Dutch nationality was arrested for the killing that revived memories of the murder of anti-immigration populist Pim Fortuyn by an animal rights activist in 2002.
Justice Minister Piet Hein Donner said yesterday the letter on the victim was a "direct warning" to Ms Hirsi Ali, who worked with Van Gogh on a film accusing Islam of encouraging violence against women and describes herself as an ex-Muslim.
The letter said Dutch politics was dominated by Jews and accused VVD parliamentary leader Mr Jozias van Aartsen as viewing "non-Jews as non-people", and Amsterdam Mayor Cohen of following an ideology that allowed Jews to lie against non-Jews.
Another letter found with the suspect said: "To the hypocrites I say, wish death or shut your mouth."
Dutch news agency ANP quoted the suspect's lawye ras calling the publication of the letters "outrageous and disturbing" and said it ran counter to good legal practice.
De Telegraafsaid both Ms Hirsi Ali and Mr Wilders, an outspoken maverick seen as a new Fortuyn, had been taken to safe houses. Both had been repeatedly threatened in recent months.
A man was sentenced to jail last month for threats against Ms Hirsi Ali.