A German woman who joined the Islamic State (IS) group has been jailed for nine years for crimes including keeping a Yazidi woman as a slave.

The defendant was also found guilty of crimes against humanity and membership of a foreign terrorist organisation.

A court in the western city of Koblenz said the 37-year-old had abused the young Yazidi woman for three years while they lived in Syria and Iraq.

It also found she had encouraged her husband to rape and beat the woman.

"All of this served the declared purpose of IS, to wipe out the Yazidi faith," said prosecutors at the start of the trial in January.

In 2014, IS fighters stormed into the ancestral homeland of the Yazidi religious minority in northern Iraq's Sinjar region and launched what the UN has said was a genocidal campaign.

Thousands of men and boys over the age of 12 were summarily killed after being given the ultimatum to convert or die. Some 7,000 women and girls were enslaved and subjected to brutal abuses.

Among them was the young woman whom prosecutors said the accused, named as Nadine K, and her husband used as a slave from 2016, when they moved to the northern Iraqi city of Mosul.

They had travelled to Syria to join IS a year earlier and later moved back there with the woman, who was in her early 20s at the time.

In March 2019, Nadine K and her family were captured by Kurdish forces in Syria. She was arrested last year after being repatriated to Germany.

During her trial, the accused denied coercing the Yazidi woman but said she should have done more for her.

The victim, who was freed in 2019, testified in Nadine K's trial in February and was present for Wednesday's verdict.

Her lawyer said her client hoped that all of those who had committed similar crimes would be brought to justice, according to the Associated Press news agency.

There have been a number of trials in Germany recently involving former IS members accused of killing or abusing Yazidis.

In October 2021, a woman was jailed for 10 years over the killing of a Yazidi girl she and her husband had bought as a slave.

A month later, a German court issued the first worldwide ruling that recognised crimes by IS against the Yazidi people as genocide.