Turkey will join an international coalition against neighbouring Syria even if the UN Security Council fails to reach consensus on the issue, its foreign minister said in an interview published Monday.

"If a coalition is formed against Syria in this process, Turkey will take part in it," Ahmet Davutoglu told the Milliyet newspaper.

UN experts were due to start investigating a suspected Syrian chemical attack on Monday, a day after the Syrian authorities approved the inspection.

Syria's opposition says more than 1,300 people died when regime forces unleashed chemical weapons against rebel-held towns east and southwest of Damascus Wednesday. Doctors Without Borders said at least 355 people had died of "neurotoxic" symptoms.

Damascus has strongly denied it carried out such an attack, instead blaming the rebels.

And a sceptical Washington weighing military action and coordinating with allies said Syria's acceptance of the probe came too late.

Davutoglu, whose country is one of the most vocal critics of Syrian President Bashar al-Assad's regime, said Ankara was awaiting the results of the UN inspection.

"After the inspection, the UN Security Council needs to make a decision on sanctions. We always place priority on acting upon a UN resolution and together with the international community," the foreign minister said.

But he warned: "If there's no such decision ... other options will be on the agenda. 36-37 countries have already been discussing these options."

Permanent UN Security Council members Russia and China have repeatedly blocked resolutions on Syria throughout the 29-month-old crisis in the country and Moscow in particular is one of Damascus's regime strongest supporters.

Turkey shares a 910-kilometre (560-mile) border with Syria and is one of the key states that is most affected by the civil war right on its next door.

It has taken in around 500,000 refugees as well as army defectors and has repeatedly called on the international community to act on the crisis.

"Turkey has been insisting since the very beginning the international community should not remain indifferent to the massacres of the Assad regime," Davutoglu said.

"Those who commit war crimes and crimes against humanity must definitely be punished," he added.

"When we look at what's happening in Syria, we see the Assad regime resorting to methods that go beyond the inhuman acts and massacres committed in Bosnia" in the 1990s.