More than 10,000 Islamic State fighters have been killed since the international coalition started its campaign against the militant group nine months ago in Iraq and Syria, US Deputy Secretary of State Antony Blinkensaid on Wednesday.

Speaking after the coalition met in Paris, he said there had been a great deal of progress in the fight against Islamic State but that the group remained resilient and capable of taking the initiative.

"We have seen a lot of losses within Daesh since the start of this campaign, more than 10,000," Blinken said onFrance Inter radio, using a mildly derogatory term for Islamic State. "It will end up having an impact."

On Tuesday, Western and Arab states carrying out air strikes on Islamic State fighters backed Iraq's plan for retaking territory after being accused by the Iraqi premier of not doing enough to help Baghdad push back the insurgents.

"At the start of this campaign (we) said it would take time," he said. "We have conceived a three-year plan and we're nine months into it."