By Geraldine Coughlan
BBC, The Hague
A letter left on the body of murdered Dutch film-maker Theo van Gogh contained death threats against a Dutch politician, the justice minister says.
The letter contains Koranic verses translated into Dutch
Piet Hein Donner said the letter, pinned to Mr Van Gogh's body with a knife, was "a direct warning" to the liberal deputy Ayaan Hirsi Ali.
Mr Van Gogh was shot dead in Amsterdam on Tuesday.
Nine suspects, all believed to be radical Islamists, have been arrested in connection with the murder.
Mr Donner said the letter was signed by an unknown group.
Ms Hirsi Ali is a Somali refugee who wrote the script to Mr Van Gogh's controversial film Submission, which criticises the treatment of women under Islam.
Mr Van Gogh, the great-great-nephew of the 19th-century artist Vincent van Gogh, received death threats after the film was broadcast on national television in August.
The letter threatened to bring down "non-believers".
It was typed in Dutch and contained Koranic verses written in Arabic and translated into Dutch.
The letter threatens Ayaan Hirsi Ali, Van Gogh's scriptwriter
Another letter found with a suspect arrested in the case is a farewell letter stating that he is prepared to die as a martyr for his faith.
The authorities are investigating possible links between the nine suspects who have been arrested and foreign terrorist groups, including those responsible for the Casablanca bombings in May last year.