PARIS (Reuters) - Defence chiefs from the United States, France, Britain and four other countries pledged on Wednesday to intensify their fight against Islamic State, looking to capitalise on recent battlefield gains against the militants.

A fighter of the Islamic State of Iraq and the Levant (ISIL) holds an ISIL flag and a weapon on a street in the city of Mosul, June 23, 2014. REUTERS/Stringer

The jihadist group lost control of the western Iraqi city of Ramadi last month, in a sorely needed victory for U.S.-backed Iraqi forces. But critics, including some in the U.S. Congress, say the U.S. strategy is still far too weak and lacks sufficient military support from Sunni Arab allies.

Sunni Arab nations have largely dropped out of the air campaign against Islamic State since last year joining a Saudi-led coalition fighting Houthi rebels in Yemen.

“We agreed that we all must do more,” U.S. Defense Secretary Ash Carter told a news conference after talks in Paris among the “core” military coalition members, which also included Germany, Italy, Australia and the Netherlands.

A U.S. defence official, speaking on condition of anonymity, said the United States was looking for additional contributions of special operations forces from allies. The official also signalled a willingness among core contributors to consider providing additional police and military trainers as needed.

A joint statement by the ministers re-committed their governments to work with the U.S.-led coalition “to accelerate and intensify the campaign.”

The Paris setting for the talks itself sent a message, coming just over two months after the city was struck by deadly shooting and bombing attacks claimed by Islamic State.

French Defence Minister Jean-Yves Le Drian said Islamic State was in retreat. “Because we have been able to hit its resources, it’s now time to increase our collective effort,” he said.

British Defence Secretary Michael Fallon said the goal was now to “tighten the noose around the head of the snake in Syria in Raqqa.”

COALITION ‘NOT WINNING YET’

But U.S. Senator John McCain, the chairman of the Senate Armed Services Committee - along with other critics of U.S. President Barack Obama’s approach to the war effort - says Islamic State still poses a potent threat.

“ISIL has lost some territory on the margin, but has consolidated power in its core territories in both Iraq and Syria,” McCain said at a Wednesday hearing on U.S. war strategy, using another acronym for Islamic State.

“Meanwhile, ISIL continues to metastasize across the region in places like Afghanistan, Libya, Lebanon, Yemen, and Egypt. Its attacks are now global, as we saw in Paris.”

Carter has sought to confront Islamic State both by wiping out its strongholds in Iraq and Syria and addressing its spread beyond its self-declared caliphate there.

But U.S. officials have declined to set a timeline for what could be a long-term campaign that will also require political reconciliation to succeed.

Carter announced a meeting next month of defence ministers from all 26 military members of the anti-Islamic State coalition, as well as Iraq, in what he described as the first face-to-face meeting of its kind.

“Every nation must come prepared to discuss further contributions to the fight,” he said. “And I will not hesitate to engage and challenge current and prospective members of the coalition as we go forward.”

The U.S. defence official acknowledged that the need for a greater Arab role was a focus of discussions and held out hope that Saudi Arabia would attend next month’s talks in Brussels.