Saudi Arabia says a coalition of 34 Islamic nations has not ruled out providing ground forces in the fight against Islamic State.
Saudi Foreign Minister Adel al Jubeir said the alliance would share intelligence and train, equip and provide forces if necessary.
"Nothing is off the table," he said, when asked if the action would provide troops on the ground, though it is unclear exactly how the coalition will work.
"It depends on the requests that come, it depends on the need and it depends on the willingness of countries to provide the support necessary," he said.
The minister said there was "no limit in terms of where the assistance would be provided, or to whom it would be provided", and that requests for assistance from members would be dealt with on a "case-by-case basis".
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He added "discussions" were ongoing about sending some special forces into Syria as part of the US-led efforts to fight IS.
Egypt, Qatar, the United Arab Emirates, Turkey, Malaysia, Pakistan and several Gulf Arab and African states make up the coalition, a joint statement said.
Published on state news agency SPA, it said: "The countries here mentioned have decided on the formation of a military alliance led by Saudi Arabia to fight terrorism, with a joint operations centre based in Riyadh to coordinate and support military operations."
The announcement said there was "a duty to protect the Islamic nation from the evils of all terrorist groups and organisations whatever their sect and name which wreak death and corruption on earth and aim to terrorise the innocent."
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Iran, a mainly Shia Islam country, Iraq and Syria were absent from the list.
Syrian President Bashar al Assad remains opposed to negotiating with groups he sees as terrorists, but there are hopes Russia may force him to make concessions.
On Tuesday, US Secretary of State John Kerry was in Moscow for talks with his opposite number Sergei Lavrov and Russian President Vladimir Putin to try to extract from them an agreement that while Mr Assad should probably go, much of his regime could be preserved.