WASHINGTON (AFP) - US intelligence warned in May that the Islamic State in Iraq and Syria (ISIS) had developed the capability to carry out the kind of attack claimed by the extremist group in Paris and explicitly picked out the alleged mastermind.

An assessment published by the Office of Intelligence and Analysis, in coordination with the FBI, makes reference to Abdelhamid Abaaoud, the suspected ringleader of Friday's coordinated suicide bombings and shootings in the French capital that killed at least 129 people.

The report focuses on the lesson learned from a plot disrupted by the Belgian authorities in January in several cities and called it "the first instance in which a large group of terrorists possibly operating under ISIL direction has been discovered", using another name for ISIS.

It added that the plot "may indicate that the group has developed the capability to launch more complex operations in the West", as opposed to so-called "lone wolf" attacks or assaults by smaller or less sophisticated groups.

The threat was more acute in Europe than the United States, the assessment said, but cautioned that "we cannot discount the possibility for potential complex attacks here in the Homeland".

The report, citing European media, called Abaaoud the purported leader of the Belgian plotters and said he directed operations from a safehouse in Athens using a cell phone, possibly in a bid to hide his involvement.

Investigations into the group's activities spanned several European countries, including France, it said.