"The raid ... including 10 fighter jets, was launched simultaneously from the United Arab Emirates and Jordan. Twenty bombs were dropped," the statement said, adding that the mission had taken place on Sunday evening.

The operation, carried out in coordination with US forces, struck a command centre, recruitment centre for jihadists, a munitions depot and a training camp for fighters, it said. 

The attackers in Friday's terrorist assault in Paris communicated at some point beforehand with known members of the Islamic State in Syria, officials on both sides of the Atlantic say, adding evidence to the assertions that the radical group coordinated or helped carry out the attacks rather than simply inspired them.

President Francois Hollande of France has characterised the attacks as "an act of war" carried out by Islamic State, also known as ISIS or ISIL. He provided no specific information, but the Islamic State released statements on Saturday claiming responsibility for the attacks, part of increasing indications that the group is becoming more capable of extending its reach far beyond its base in Syria and Iraq.

"It is an act of war that was prepared, organised and planned from abroad, with complicity from the inside, which the investigation will help establish," Mr Hollande said on Saturday.

While the information made available so far about the links between Islamic State and the Paris attackers was not definitive, it suggested at a minimum that the assailants had not acted totally on their own.

Describing the case for the group's role, US and French officials said the attackers had operated with high levels of sophistication, beyond what would be expected of a plot in which the assailants were merely inspired to act by a radical group rather than trained or equipped by it.

The attackers are believed to have communicated using encryption technology, according to European officials who had been briefed on the investigation but were not authorised to speak publicly. It was not clear whether the encryption was part of widely used communications tools, like WhatsApp, which authorities have a hard time monitoring, or something more elaborate. Intelligence officials have been pressing for more leeway to counter the growing use of encryption.

The disciplined way some of the attackers handled themselves during the assault and evidence of some military-style training - for example, having one attacker continue shooting while another reloaded his weapon - also suggested that the plot involved considerable planning and input from an organised group, a French official said.

Following the attacks, intelligence and law-enforcement agencies reviewed intercepted communications and concluded that the attackers had been in touch with members of the Islamic State in Syria, US and French officials said.

Reuters, New York Times