A US special forces raid in eastern Syria killed 32 members of the Daesh jihadist group, including four leaders, a monitoring group said Sunday.

"The US operation killed 32 members of IS, among them four officials, including IS oil chief Abu Sayyaf, the deputy IS defence minister, and an IS communications official," said Rami Abdel Rahman, head of the Syrian Observatory for Human Rights.

US officials have said "about a dozen" people were killed in the operation.