THE HAGUE, Netherlands -- Dutch authorities detained seven terrorist suspects believed to be plotting attacks on politicians and the bombing of a government building, officials said. Bart Nieuwenhuizen of the Dutch National Prosecutor's office told CNN that those held were suspected Islamic radicals believed to be planning a number of attacks. The chief suspect in the raids in three cities was Samir Azzouz, a 19-year-old Dutch national of Moroccan descent who was acquitted of terrorism charges earlier this year, Nieuwenhuizen said.Azzouz was allegedly in the process of purchasing automatic weapons and explosives, "probably to commit assaults on several politicians and a government building," he said.Around two dozen officers in riot gear closed entrances leading to both houses of parliament and the government's information service. The weekly Cabinet meeting, however, went ahead as scheduled. Frits Wester of RTL news told CNN the suspects were six men between 20 and 30 years old and one woman aged 24.He said the group under suspicion were Islamic fundamentalists who had issued a number of death threats against the authorities and members of parliament.On Thursday, media reported renewed threats against MPs Ayaan Hirsi Ali and Geert Wilders, both outspoken critics of Islamic extremism. The two went into hiding for several months after Dutch filmmaker Theo van Gogh's brutal murder on an Amsterdam street, a year ago next month. The suspects were detained in The Hague, Amsterdam and Almere, The Associated Press reported. They will be brought before an investigating judge Monday. Police declined to confirm media reports of gunfire in the largely immigrant Schilderswijk neighborhood in The Hague where a hand grenade exploded during the arrest of two terrorist suspects last year, following van Gogh's murder. Journalist Hans Andringa told CNN there had been rumors that on November 2, the anniversary of Van Gogh's death, fundamentalists were planning "a macabre birthday party."Following the arrests, Holland's National Coordinator for Counterterrorism announced a stepping up of security around the Binnenhof (parliamentary and governmental complex in The Hague), the headquarters of the General Intelligence and Security Service in Leidschendam, the Ministry of Justice and the Ministry of the Interior and Kingdom Relations.Personal security was also being stepped up for leading figures, the statement said, adding that there was no need to raise the general threat level associated with the national terrorist threat assessment. "As reported earlier, the current threat level for the Netherlands is substantial, and that level remains unchanged," the statement said.CNN's Andrew Carey contributed to this report.Copyright 2005 CNN. All rights reserved.This material may not be published, broadcast, rewritten, or redistributed. Associated Press contributed to this report.