Heiko Maas didn't further identify the women or children, who were flown back to Germany on Saturday.

However, the German weekly Bild am Sonntag reported that all three women had left Germany in recent years to join the extremist Islamic State group in Syria. The paper identified the women as Merve A., Yasmin A. and Leonora M.

Also Sunday, Germany's federal prosecutor's office said a German citizen by the name of Leonora M. had been arrested upon her arrival at Frankfurt airport. It said she is accused of IS membership and allegedly committed crimes against humanity.

Maas said he was “very relieved” about the return of the 12 children and three of their mothers. He said the return was organized in cooperation with Finland, which brought home six children and two women.

“These are humanitarian cases, especially orphans and children with illnesses — cases in which the departure was urgently needed,” Maas said.

“This good news just before Christmas makes us confident that we will be able to organize the return of further cases as well," he said.

Hundreds of Europeans — many of them young women — left the continent in the last couple of years to join IS and fight in Syria and Iraq. Several died while others were arrested and detained by Turkish, Kurdish or Iraqi authorities who have been eager to deport them and their children back to Europe.

European governments, however, have been reluctant to take back the often-radicalized IS supporters.

The Finnish government said Sunday the repatriation of its citizens from the al-Hol camp in Syria was done for humanitarian reasons and because of the country's legal obligations for its citizens.

“The basic rights of the children interned in the al-Hol camps can be safeguarded only by repatriating them to Finland,” the Finnish government said in a statement.

No identities of the children or women were given, but Finnish officials said they consisted of two families.

Jussi Tanner, the Finnish Foreign Ministry’s special representative in charge of making the repatriation decision, stressed at a news conference that the Syria camps formed a highly complex case judicially for Finland and other Western countries..

“No such world exists where we are able to repatriate children only,” Tanner said, referring to parents’ legal rights to their children. He said Finland opted to cooperate with Germany as the two countries had common interests in the case and share similar legislation.

The two returning women, which Finnish media said are both known to be radicalized IS sympathizers, will face thorough screening by security officials upon return.

The Finnish newspaper Helsingin Sanomat said Sunday that Finnish security police consider both of them “a security threat." It marked the first time that Finland repatriated adults from Syrian camps apart from orphaned children.

The women and children who just arrived in Germany were detained at the al-Hol and Roj camps in northeastern Syria, the German foreign ministry said. The camps are managed by the Kurdish-led administration in northeastern Syria, but lack basic services and have been rife with diseases and lawlessness.

Al-Hol holds more than 60,000 Syrian, Iraqi and Western detainees, most either family members of IS fighters or supporters of the group who had remained in the territories it held until the final battle in March last year. In late 2019, Finland repatriated two orphans from the al-Hol camp. Around 15 Finnish children and five adults still remain there, Finnish officials said Sunday.

Roj is a smaller camp with mostly Westerners — also family members of imprisoned or killed IS fighters or supporters.

The Kurdish-led authorities said last month they would begin releasing some of the 25,000 Syrians held in the al-Hol camp, allowing them to return home if they choose to.