Police have arrested a 31-year-old woman in Uithoorn who they say is probably one of the managers of an IS support group on the encrypted social media network Telegram.

The group, named GreenB1rds spreads IS propaganda, films about how to make a bomb vests and carries news items supplied by the organisation’s official press office, the public prosecution department said.

The woman is also suspected of helping during a training session to prepare for a terrorist attack. ‘She is already the subject of a criminal investigation because in 2015 she went to Syria and joined up with IS,’ the public prosecutor said.

Police also found an IS flag, a stun gun and pepper spray during a search of her home.