Mosul, Nov 13 (IANS/AKI): Thousands of women from the Yazidi minority are being held by the Islamic State jihadist group in the embattled Iraqi city of Mosul, local news site Ara News reported, citing a prominent human rights activist.

"A total of 3,400 Yazidi women and girls remain enslaved for IS sex use. Only a few have escaped since the Mosul operation," Ara News quoted Nadia Murad as saying on Friday.

Murad said she recently been receiving calls from Yazidi families asking for help to free their women and girls from IS captivity.

"A Yazidi mother told me her 16-year-old daughter's rescue from IS sex slavery costs 15,000 dollars and she cannot pay," she said.

"It is unbearable," said Murad, who survived IS enslavement and was nominated for this year's Nobel Peace prize for her efforts to alleviate the plight of Yazidi women at the hands of IS.

Yezidi women are reported to have been moved to Mosul for use as human shields as well as sex slaves, the United Nations human rights office said on Friday describing the scale of civilian suffering in the IS stronghold as "numbing and "intolerable".

IS executed over 60 people this week for alleged "treason" in Mosul after rulings by the so-called IS 'courts' according to the UN. Other reported atrocities include torture, chemical attacks, large-scale use of human shields and sexual exploitation of women and girls.

The Iraqi army, Kurdish Peshmerga forces, Sunni Arab tribesmen and Shia militiamen in mid-October began an operation to route IS militants from Mosul, and last week entered the eastern outskirts of the city, which IS overran in 2014.

Kurdish forces have recently discovered several mass graves in the Yezidi Sinjar region of Iraq. IS attacked Sinjar in August 2014, murdering hundreds of people and abducting thousands of women and girls who they forced into sexual slavery.

Almost 4,000 Yazidis who were enslaved remain unaccounted for, the UN said in August.