Dutch lawmakers accused the government Thursday of underestimating the threat from Islamic terrorists and failing to protect a filmmaker slain by a suspected Muslim radical.

In a parliamentary debate about Theo van Gogh's (search) murder last week, lawmakers from both opposition and government parties urged Premier Jan Peter Balkenende (search) to take urgent steps to increase public safety and restore confidence in the law.

The Nov. 2 killing triggered a cycle of retaliatory attacks on Islamic buildings and Christian churches that shocked this traditionally peaceful and tolerant nation.

"When it comes to preparing a terrorist attack, it's better to have 10 possibly innocent people temporarily in jail than one with a bomb on the street," said Maxime Verhagen, the floor leader of Balkenende's own Christian Democrats.

Jozias van Aartsen, leader of Balkende's Liberal allies, urged the government to close mosques where imams preach violence, shut down Web sites that spread antidemocratic ideas and beef up the intelligence services.

"The Netherlands used to be an island of decency and tolerance," he said. "Not all Muslims are terrorists ... but there are a large number of terrorists in this world that feel attached to an identity as Muslim. They want to destroy us."

Interior Minister Johan Remkes was widely accused of weak leadership for not giving police protection to Van Gogh, who had received death threats in April for his criticisms of Islam. Van Gogh's latest film, "Submission," was released in August and criticizes the way Islam treats women.

On Thursday, the government said the main suspect in the killing, Mohammed Bouyeri, 26, was a peripheral figure in an Islamic terrorist network in Amsterdam who merited no close surveillance.

It said it briefly monitored his cell phone conversations until two weeks before Van Gogh's slaying and knew he consorted with Muslim extremists.

"It is a disgrace that we know potential terrorists are running free in this country," said Geert Wilders, a right-wing lawmaker.

He called on the government to arrest the 150 or so Muslim extremists on its watch list.

A harsh critic of Islamic fundamentalism, Wilders has gone into hiding since Van Gogh's murder, except for during the parliamentary debates, when he is escorted by bodyguards.

Also hiding is Somali-born Ayaan Hirsi Ali, a conservative legislator, who collaborated with Van Gogh on "Submission."

Van Gogh's killer left a note impaled on the filmmaker's chest threatening further attacks on Dutch politicians in the name of fundamentalist Islam.

Before the debate, Justice Minister Piet Hein Donner announced new steps to make it easier to infiltrate terrorist networks.

He said Van Gogh's murder and the arrests this week of 13 terrorist suspects "clearly showed more powers are needed to combat terrorism."

Under Donner's new draft law, investigators will not have to prove they have a "reasonable" suspicion of terrorist activities in order to conduct searches and detain people — "indications" will suffice.

Donner also proposed making it easier to access bank accounts of suspects and for police to make preventive searches of vehicles near popular sites.

The murder of Van Gogh, a distant relative of Dutch impressionist painter Vincent Van Gogh (search), has triggered at least 17 attacks against Muslim schools and mosques and Christian churches. A public elementary school and a church were targeted by arsonists Wednesday, while an elementary school classroom was seriously damaged in Eindhoven, the site of a bombing of a Muslim school earlier this week.