Sunni Arab smugglers in Syria are helping to rescue Yazidi women and girls abducted from northern Iraq by Islamic State (IS) militants, but often charge large sums of money for their services, Yazidi activists say.

"It's a sort of rescue operation," says Murad Ismael of the Yazidi NGO Yazda, which works to support displaced Yazidis in Iraqi Kurdistan.

But for Yazidi captives fortunate enough to get the chance, such a rescue often comes at a price. Fees vary: Ismael says some smugglers have reportedly charged as much as $15,000, though most demand around $1,000 per captive.

Hayri Demir, editor in chief of Ezidi Press, also says Syrians demand high fees. A Yazidi group in Germany reportedly paid 20,000 euros ($22,540) to a smuggler near the IS-held city of Deir al-Zor to free a Yazidi girl, Demir says, though he called that a special case because the smugglers knew the Yazidis paying for the rescue were in Europe.

Rescue From Raqqa

Most -- it is not known exactly how many -- of the Yazidi girls and women abducted by IS are thought to have been taken from Iraqi Kurdistan to Syria, usually to Raqqa, the extremist group's de facto capital, and to Deir al-Zor, another IS stronghold. Once in Syria, IS militants buy and sell Yazidi women and girls as sex slaves.

Though the people-smuggling networks are expensive and risky, activists say that Yazidis have no choice but to use them. "The only way to bring the ones in Raqqa back is to bring them with money," Ismael says.

Coming up with the cash is not easy. Usually, Yazidi families have to raise the money to pay for the smugglers themselves, according to Ezidi Press's Demir.

"Most of the [Yazidi] families haven't enough. Sometimes the KRG [Kurdish regional government] paid, but often the families have to round up the money themselves," Demir says.

Who Are The Smugglers?

According to Demir, most of the people smugglers are local Sunni tribespeople. "These are often loyal to [IS] but make their money smuggling these women, but among them there are also some Sunnis who helped women without money," Demir tells RFE/RL.

Yazidi NGO leader Ismael emphasizes that some Sunnis have helped rescue Yazidi women for no charge, even though they face death if IS catches them. "Sunni Arabs in Syria are risking their lives [to save Yazidis]," he says.

The Kurdistan Workers Party (PKK) and the Syrian Kurdish People's Protection Units (YPG) have also assisted Yazidi families and activists who are trying to rescue captive women and girls from IS's clutches. "The PKK and YPG provide frequently the contact to these smugglers," Demir says.

Yazidis say that the PKK, considered a terrorist group by Turkey, the United States, and the European Union, also helped Yazidi refugees flee IS in August, in the immediate aftermath of the IS invasion of Sinjar. The PKK and YPG helped Yazidis to cross into Turkey, according to reports.

Captured By IS, Sold Back By IS

The smuggling of Yazidi women for money has developed into a market of "slavery and human trafficking," Demir says.

But beyond the smugglers who are demanding payment for rescuing Yazidis, IS militants themselves have also sold Yazidi captives back to their families, according to recent reports.

In an unexpected move on April 4, IS released 217 Yazidi captives, most of them women and children.

However, United Nations human rights officials say the release of the Yazidis was not a benevolent move. Instead IS insisted on receiving cash payments for the captives, which it insisted were slaves who must be sold, not ransomed.

UN human rights chief in Iraq Francesco Motta told VICE News that IS regarded those Yazidis who had not converted to Islam as "malak yamiin," or slaves. "All were taken before a so-called Shari'a court for the 'bill of sale' to be approved prior to their release," Motta was quoted as saying.

Motta added that the sale of Yazidis was carried out by intermediaries in areas under IS control.

Escape, And Someone Else Dies

While Syria's smugglers put a cash charge on freeing them, many Yazidis who have tried to escape IS have ended up paying a far higher price. The extremist group has put to death Yazidi women who have tried but failed to escape, while others have been beaten and tortured.

The threat of personal risk has not stopped captives from trying to escape.

Officials from the Iraqi Kurdish Peshmerga militia said last month that dozens of Yazidis had managed to escape Tal Afar after being helped to flee by an Arab family. Other escapes have also been reported.

But activists with contacts among Yazidi captives say that IS has now found a deterrent to prevent captives in Iraq from fleeing. Following the escapes from Tal Afar, near Mosul, IS instituted a crackdown.

Ismael says that a recent ruling issued by an IS Shari'a court decrees that whenever a Yazidi escapes IS captivity, IS will kill another Yazidi hostage.

Since the ruling, no one else has escaped from Tal Afar, according to Ismael.

Also in response to the Tal Afar escapes, IS separated hundreds of male Yazidis from women and girls, prompting fears that IS could be about to kill them.

Last week, Yazidi activists criticized news reports that IS had carried out a mass killing of the Yazidi men, saying that there had been no confirmation that this had taken place.

Men and boys over 9 years of age were reportedly called to the mosque in Tal Afar and taken away from their families. Activists heard reports that IS's "wali" (custodian) in Tal Afar had issued a ruling to execute the men, but Ismael says that there has been no confirmation that this has been carried out.

Other reports said that IS's Shari'a court in Raqqa had said the Yazidi men's lives should be spared if they convert to Islam, according to Ismael.

But it is still not clear what has happened to the Yazidi men. "The men are still missing," Ismael says.

From Rescue To Refugee

While the people-smuggling networks have managed to rescue Yazidi girls and women from IS, thousands more remain kidnapped. And though they are free from IS captivity, escaped Yazidi women and girls face dire conditions as displaced persons in Iraq's Kurdistan region.

On a recent trip to Dohuk in Iraq's Kurdish region, on whose outskirts around 350,000 displaced persons are living, Ismael says he met with around 30 Yazidi escapees who were living in abandoned buildings and even tents.

The authorities in Dohuk provide escaped women with a free medical examination, and while the International Rescue Committee (IRC) is distributing aid in northern Iraq, many Yazidi escapees cannot afford the taxi fare into the center of Dohuk to access the IRC's services.

Overstretched by the war against IS, and with no presence in Dohuk, the Iraqi government is doing little to help Yazidi escapees, Ismael says.

On May 2, Baghdad agreed to provide monthly payments of less than $100 per month to Yazidi women who escaped IS. But so far only 189 applications have been approved.

Ismael says that the United States and Europe must do more to stop IS's brutalities not just against the Yazidis but against all Iraqis and Syrians. "We want IS to be destroyed, because if not, the pain and suffering will continue. IS is a cancer that has to be removed," he adds.

IS militants abducted thousands of members of the Kurdish Yazidi minority, followers of an ancient religion derived from Zoroastrianism, after taking control of the Sinjar region of northern Iraq in August 2014, according to Iraqi Kurdish officials and community leaders.

The United Nations estimated that by October IS fighters had killed upwards of 5,000 Yazidis and abducted as many as 7,000 more.

-- Joanna Paraszczuk