The arrests led to heightened security measures in the Netherlands around government buildings in central The Hague, which were sealed off by police, and the AIVD intelligence service headquarters.

Interior Minister Johan Remkes told a press conference that the seven suspects were members of the Hofstad group. Thirteen people are already in custody awaiting trial on charges of belonging to the group, including the convicted murderer of Dutch filmmaker Theo van Gogh.

"The intelligence services have established that despite earlier arrests this network has continued its activities. The group has grown in size in the last year and does not only consist of young men but also of young women," Remkes said.

Justice Minister Piet Hein Donner said the Muslim community in the Netherlands should not be blamed for the suspects' activities and appealed for calm.

"Everything points to the fact that the suspects acted and wanted to act based on an extreme religious ideology. I want to stress that this is a handful of people who, in my opinion, abuse

the Islamic faith to justify their actions," he said.

Gathering weapons

The suspects, six men and a woman, were arrested in The Hague, Amsterdam and nearby Almere, the national prosecutor's office said in a statement.

The main suspect according to the authorities is 19-year-old Samir Azzouz, who was acquitted of charges of planning terrorist attacks because of insufficient evidence in April.

"Information of the AIVD intelligence service showed (Azzouz) was trying to get automatic firearms and explosives," the prosecutor's office said.

"He is suspected of preparing attacks, together with other persons, on several politicians and government buildings."

A second suspect arrested Friday was Jermaine Walters, his lawyer told Dutch national public Radio 1. Walters had also been arrested in the first Hofstad group case but was released later

after prosecutors said there was not enough evidence to hold him.

His older brother Jason Walters, like Jermaine a recent convert to Islam, is suspected of constituting the core of the Hofstad group together with Mohammed Bouyeri, Van Gogh's murderer. He is still in custody awaiting the first Hofstad group trial set to start December 5.

During one of the arrests in The Hague, witnesses reported hearing gunshots but the NOS national public television reported that the police had fired flares to create confusion which would explain the noises heard.

Monday court date

The suspects arrested Friday, including Azzouz, were to appear in court Monday in Rotterdam for a procedural hearing to see if they can be remanded in custody.

With the exception of Azzouz, the national prosecutor's office declined to identify the other suspects other than to say the men were between 18 and 30 years old and the woman was 24.

In a related development Friday, a court ruled that Van Gogh's murderer Mohammed Bouyeri (photo) can be tried a second time on terrorism charges despite the fact that he is already serving the maximum sentence of life in prison without the possibility of parole.

The murder of the outspoken Van Gogh, who sharply criticized Islam, on November 2 2004, profoundly shocked the Netherlands and caused a flare-up of ethnic tensions in the usually easy-going country. Many Dutch saw the brutal murder as a sign that Islamic extremism was spreading in their country.