Up to 10,000 women and girls in Iraq have been abducted or trafficked for sexual slavery, prostitution or ransom, rights groups said on Wednesday, as they called for the Iraqi government to crack down on crimes against women.

Campaigners estimate some 14,000 women have been killed since the U.S.-led invasion of 2003, and many women and girls — including children as young as four - have been raped in that time.

Some women have been so traumatized that they have committed suicide, according to a report by Minority Rights Group International and the Ceasefire Center for Civilian Rights.

The authors say trafficking in Iraq has "mushroomed" in recent years and that the militant Sunni group Islamic State (ISIS) has become a major actor in the buying and selling of girls.

Mass displacement, economic desperation and the breakdown of law and order have created a ripe environment for traffickers.

Displaced women are particularly vulnerable, as are those who have fled domestic violence or forced marriages.

Some traffickers look for runaway girls in public places such as markets, the report says. Others operate in prisons by posting bail for jailed women and forcing them into prostitution to pay back their debt.

Women trafficked across Iraq end up in Baghdad or northern Iraqi cities or are sent to Syria, Jordan or the United Arab Emirates.

A common trafficking method is for a man to marry his victim through a temporary (mut'a) marriage. Once they reach their destination he divorces her, forces her into prostitution and returns to Iraq to repeat the process.

Outside Iraq, women are sold for up to $20,000. Inside Iraq men may pay $200-$500 for a night with a virgin, according to an Iraqi rights group. In some cases girls have been forced to undergo hymen reconstruction surgery so they can be re-trafficked as virgins.

The report says Islamic State, which controls a swathe of Iraq and Syria, has also carried out abductions as a means of controlling populations, spreading fear and procuring wives for fighters.

ISIS captured at least 3,000 women and girls in Iraq in 2014 alone, many of them from the Yazidi minority when ISIS fighters swept through the northern Sinjar region, the authors say.

"ISIS has introduced and legitimized the practice of sexual slavery on an unprecedented scale," the report adds.

Kidnapped women who managed to talk to rights activists in secret by phone in August said ISIS fighters were raping women on a daily basis. Some even begged for airstrikes on their locations to end their suffering.

One Yazidi girl told activists she was taken to Syria with 350 other girls where they were displayed and sold in the streets "as if in a chicken market."

Militants raped them repeatedly at night. Any girl who tried to commit suicide or escape was tortured with electrical cables, the report said. Many were sold to fighters from Syria, Saudi Arabia, Qatar, Chechnya or Afghanistan.

Miriam Puttick, Civilian Rights Officer at Minority Rights Group, called on the Iraqi government and the Kurdistan regional government to step up efforts to secure the release of kidnapped women.

"ISIS is not the first group to be involved in abducting and trafficking women. Women have been disappearing off the streets of Iraq by the hundred ever since the start of the conflict," she added.

"The silence of the Iraqi and Kurdish authorities on this issue must end."

The report also highlights horrific sexual violence, but says there are no figures for rape because strong taboos prevent women from reporting sexual crimes.

In one case a soldier raped a four-year-old before beating her to death with a brick. In another, a five-year-old was gang-raped and strangled with a shoelace.

The authors say the report is the first time anyone has calculated the number of women who have died in the 12 years of conflict.

Women have not only been killed in bombings, shelling and air attacks, but also singled out as targets, they say. Both Sunni and Shi'ite militias have carried out mass extra-judicial executions of women for perceived transgressions of moral codes.

The report calls for Iraq to implement legislation to combat human trafficking, toughen up laws against sexual violence and investigate crimes against women, including those committed by police, security forces and militias.