Top ISIS leader Abu Sayyaf killed by US special forces in Syria

A senior Islamic State terrorist has been killed by elite American forces in a night time raid on a building in Syria.

Abu Sayyaf was a top member of the terror group who helped the group rake in millions of pounds by directing its oil, gas and financial operations.

The crack team of special forces operatives also captured Sayyaf's wife Umm in the raid and are now holding her in Iraq.

This was the first known US special forces operation inside Syria apart from a failed secret effort to rescue a number of US and other foreign hostages held by Islamic State in northeastern Syria last year.

White House National Security Council spokeswoman Bernadette Meehan said in a statement that U.S. personnel based out of Iraq conducted the operation in al-Amr in eastern Syria.

"During the course of the operation, Abu Sayyaf was killed when he engaged US forces," Meehan said.

"The president authorized this operation upon the unanimous recommendation of his national security team and as soon as we had developed sufficient intelligence and were confident the mission could be carried out successfully and consistent with the requirements for undertaking such operations," Meehan said.

Meehan said the operation was conducted "with the full consent of Iraqi authorities" and "consistent with domestic and international law."

The White House said the US did not inform Syrian

President Bashar al-Assad's government in advance of the raid, or coordinate with Damascus. Shortly before the US announcement, Syrian state television said the Syrian army killed an Islamic State leader responsible for oil-related affairs, identifying him as Abu al-Taym al-Saudi.

Defense Secretary Ash Carter said that US special operations forces conducted the operation targeting Abu Sayyaf and his wife. Carter said Abu Sayyaf was involved in the militant organization's military operations and helped direct its "illicit oil, gas and financial operations as well."

Carter said the wife "played an important role in ISIL's terrorist activities. Meehan said during the operation US forces freed a young Yezidi woman "who appears to have been held as a slave by the couple." Meehan said the wife is now in US military detention in Iraq.

No US forces were killed or wounded during the operation, Carter said.

"The operation represents another significant blow to ISIL, and it is a reminder that the United States will never waver in denying safe haven to terrorists who threaten our citizens, and those of our friends and allies," Carter said, using an acronym for the Islamic State organization.

American and Arab forces have been carrying out almost daily air raids against hardline Islamist militant groups in Syria including Islamic State since last September, and US-led forces are also targeting the group in Iraq.