The 37-year-old German defendant, identified only as Nadine K., was also found guilty of crimes against humanity and membership of a foreign terrorist organisation, a spokeswoman for the court in the western city of Koblenz said.

The defendant was a member of IS between December 2014 and March 2019, travelling to Syria to join the jihadist group with her husband. In 2015, the couple later moved to Mosul in Iraq, then back to Syria.

From April 2016, the pair kept as a slave a Yazidi woman, who had been imprisoned by IS since 2014.

Nadine K. kept watch to prevent the woman, who was 22 at the time, from fleeing and forced her to do housework and observe Islamic rituals.

With the knowledge of the defendant, Nadine K.'s husband regularly raped and beat the Yazidi woman.

"All of this served the declared purpose of IS, to wipe out the Yazidi faith," prosecutors said at the opening of the trial earlier this year.

Nadine K. and her family are believed to have moved to Syria in autumn 2016 with their "slave" and lived in IS-controlled territory until March 2019, when they are believed to have been arrested by Kurdish fighters and the Yazidi woman was released.

The defendant was arrested in March last year upon her return to Germany in one of several repatriation operations.

A German court in November 2021 issued the first ruling worldwide to recognise crimes against the Yazidi community as genocide, in a verdict hailed by activists as a "historic" win for the minority.

The Kurdish-speaking Yazidis hailing from northern Iraq have for years been persecuted by IS militants who have killed hundreds of men, raped women and forcibly recruited children as fighters.