The Netherlands has stripped four extremists who had travelled to Syria to fight of their Dutch nationality under tough new anti-terror legislation, AFP reported Wednesday (September 13th).

"These four persons have joined a terror organisation in a conflict area," Safety and Justice Minister Stef Blok said in a statement.

"They have been declared undesirable aliens which means that it is no longer possible for them to travel to The Netherlands or any other Schengen country," Blok said, referring to Europe's passport-free zone.

Although Blok did not name the four men, Dutch media listed them as "known Syria travellers Driss B., Noureddin B., Anis Z. and Hatim R."

Driss B. and Noureddin B. were sentenced last year and Anis Z. and Hatim R. in 2015 to six years each in absentia for being members of a criminal terror organisation.

The four had previously travelled to Syria to join extremist fighters including the "Islamic State of Iraq and Syria" (ISIS), local news reports said.

Their current whereabouts are unknown.

Driss B. "is doubted to still be alive", national news agency ANP reported.

The Netherlands in March approved tough new legislation that gives the government the power to take away citizenship, even if a person has not been convicted of a crime.

The law can only be applied to people with double nationality.

Wednesday's decision still has to be approved by a judge, the Dutch government said. It was not known what other nationality the four men hold.

Some 280 Dutch citizens are believed to have travelled to join extremist groups in Syria and Iraq since 2011.

About 190 remain there but "there are probably still a number of Dutch jihadists who want to join the ISIS group or others in the Middle East", the Dutch anti-terror agency NCTV said in its latest report.