The French defence ministry has confirmed 20 bombs targeted an Islamic State stronghold in the Syrian city of Raqqa.

A total of 12 fighter jets dropped the bombs on the terror group’s de-facto capital, taking out a training camp, command centre, recruitment centre and supply depots, the French government claimed.

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A ministry statement said: “The first target destroyed was used by Daesh (another Arabic acronym for IS) as a command post, jihadist recruitment centre and arms and munitions depot.

“The second held a terrorist training camp.”

Watch video of the fighter jets taking off below

The raids were reportedly conducted in co-ordination with US forces.

The military action followed horrific and co-ordinated terror attacks in Paris on Friday that killed at least 129 people. Over 350 are injured.

France President Francois Hollande initially said the attacks were an “act of war” and that the country would launch “merciless” action against terrorism.

Merciless was a word also used by Ambassador of France to Australia, Christophe Lecourtier, who thanked the public for their support and said France “would not retreat one millimetre in the fight against terror”.

“Two days after this terrible night, we are just starting to realise what has really happened,” he told ABC News 24.

“But one thing is clear – it’s war. It’s war when innocent people are killed by a random…in a peaceful city on a Friday evening. It’s war.”

Speaking to ABC News Breakfast, Professor Greg Barton said there was a limit to what France could do in Raqqa.

“It is a civilian city of more than one million people – most of those people are effectively hostage,” he said.

“And this is a very cunning foe that uses people as human shields.”

Ultimately, ground forces would be needed to combat the threat presented by Islamic State, he said.

But, Prof Barton added, that ground strikes would likely be led by the Syrian military.

Australian Strategic Policy Institute executive director Peter Jennings said it had been “likely” the French would retaliate “quickly” after Friday’s attacks, but without support from other countries, particularly the United States, France could not “win this war on its own”.

The air raids were carried out in coordination with US forces.

“We absolutely agree that this was an act of war, and our hearts go out to the people of Paris who suffered this terrible attack,” US deputy national security advisor Ben Rhodes said.

Mr Rhodes said the United States would work with France to intensify air strikes against IS in Syria and Iraq.

“What we made clear to the French is we will be shoulder to shoulder with them in this response. They’re in our military campaign in Iraq and Syria already, ” he said.

“Clearly they want to energise their efforts. There is a French two-star general who is positioned at CENTCOM to help that coordination move forward.

“And we’re confident that in the coming days and weeks working with the French we will be able to intensify our strikes against ISIL in both Syria and Iraq to make clear that there is no safe haven for these terrorists.”

– with ABC