Slain ISIS commander's wife in US detention, 'may have enslaved' Yazidi woman

US commandos killed a senior Islamic State group leader in a nighttime raid into Syria, US officials said Saturday, as IS jihadists seized the northern part of Syria`s ancient Palmyra.

Washington: The Islamic State commander killed by the US troops in Syria raid managed the extremist organisation's illicit oil and gas sales and other financial operations, said the US State Department.

In a significant blow to the ISIS, the slain ISIS commander Abu Sayyaf was killed as US forces conducted an operation in al-Amr in eastern Syria on the direction of President Barack Obama, the US State Department said in a statement.

“Abu Sayyaf was a senior ISIL leader who, among other things, had a senior role in overseeing ISIL’s illicit oil and gas operations - a key source of revenue that enables the terrorist organization to carry out their brutal tactics and oppress thousands of innocent civilians. He was also involved with the group’s military operations,” the US State Department said.

We suspect that Um Sayyaf is a member of #ISIL, played an important role in ISIL’s terrorist activities. https://t.co/SEMorimpJq #Syria

— U.S. Embassy Syria (@USEmbassySyria) May 16, 2015

White House statement on counter-ISIL operation in #Syria http://t.co/R8nD5oNL6S — WH National Security (@NSCPress) May 16, 2015

Also, his wife Umm Sayyaf has been captured and is currently in US military detention in Iraq. The US forces also freed a Yazidi woman, who was apparently kept as a slave by the couple.

Slain ISIS commander's wife Umm Sayyaf is also said to be an ISIS member, who “played an important role in ISIL’s terrorist activities, and may have been complicit in the enslavement of the young woman”.

This is said to be the first time the US has carried out a ground operation to attack the ISIS in Syria.

The US says the operation was conducted with the full consent of Iraqi authorities and is consistent with domestic and international law.