A 33-year-old Dutch woman has been arrested at Schiphol airport on terrorism charges, news agency ANP said on Friday.

The woman, a Muslim convert, was arrested on the Bulgarian Turkish border on December 23 and is thought to have been on her way to Syria by car. She was picked up on a European arrest warrant on behalf of the Dutch authorities and had been a terrorism watch list for a longer period, ANP said.

The woman, said to be from Eindhoven, was escorted back to the Netherlands by military police and will now be questioned about her potential involvement in terrorism. She is being held in solitary confinement.

News agency AFP said earlier this month she had left a handwritten letter at her home saying that she was leaving to join the IS in Syria. A Bulgarian court ruled earlier this month that she should be sent back to the Netherlands.