AFP/ Amsterdam

A Dutch court on Thursday convicted six men of belonging to a terror network recruiting young Muslims to join the Islamic State jihadist group, sentencing them to jail terms of up to six years.

"The criminal organisation aimed to incite and recruit 'brothers' to travel to fight in Syria and financed them to that end," judge Rene Elkerbout said at the hearing, held at a heavily fortified courthouse on the outskirts of Amsterdam.

The complex verdict came in a landmark case that experts say tested the boundaries of religious and freedom of expression in the Netherlands, known for its tolerant values.

Eight men and one woman initially faced several charges including "belonging to a terrorist organisation", incitement to commit acts of terror, recruiting youngsters to join IS and undergoing military training in Syria.

They were arrested last year in a massive police probe into jihadist activities in a inner-city suburb of The Hague.

Public prosecutors said "the group together formed a criminal and terror organisation."

"They all had different roles and eventually contributed to the aims of the organisation," prosecutors said in a statement.

A three-judge bench agreed and sentenced the main defendant Azzedine Choukoud, 33, to six years in jail, together with two of the other suspects.

The other accused were sent to prison for between five and three years. The woman was given a seven-day jail term for writing an inciting message.

Two of the men, aged 24 and 26, are still believed to be fighting in Syria and were tried in their absence. They were also both sentenced to six years in jail.

Mostly from The Hague's inner city Schilderswijk suburb, the suspects maintained their innocence, claiming religious freedom and freedom of opinion allowed them to proclaim a pro-IS message.

The case comes after concerned parents in Schilderswijk filed a missing persons reports with the police in 2013, launching the biggest Dutch probe to date into radical Islamist activities.

At the time, many of the accused were involved in pro-IS protest marches in the neighbourhood, also posting messages of support on social media sites such as Facebook and Twitter.

At least 220 Dutch citizens have left the Netherlands for Syria and Iraq to join fighters there, the Dutch National Coordinator for Security and Counterterrorism (NCTV) said.