Sybrand van Hulst, head of the AIVD, was quoted by the daily newspaper Het Parool as saying he believed several dozen of those radicals were prepared to use violence, and that the AIVD had difficulty combating them.
Since the Nov. 2 murder of Theo van Gogh, a Dutch filmmaker critical of Islam, Hulst has accused politicians of ignoring intelligence warnings about rising Islamic militancy in the country.
A 26-year-old Dutch-Moroccan has been charged with van Gogh’s killing, which was followed by a wave of attacks on mosques and Muslim schools and retaliatory attacks on churches.
The AIVD has warned that the integration of immigrants is failing and that foreign powers are trying to influence religious communities in the Netherlands. Van Hulst says young men are especially vulnerable to the appeal of radical Islam.
The Netherlands is home to about 1 million Muslims, or 6 percent of the population.