DAMASCUS (AFP) - Syria's army is ready for potential foreign strikes against it and has its "finger on the trigger", Prime Minister Wael al-Halqi said in comments carried on Saturday over state television.

"The Syrian army is fully ready, its finger on the trigger to face any challenge or scenario that they want to carry out," he said in a written statement aired on television.

Damascus has ratched up the rhetoric as the world waits to see if the United States and others decide to strike it in retaliation for a suspected gas attack blamed on the regime.

United Nations inspectors probing whether an August 21 attack actually happened left Syria earlier on Saturday, opening a window for a possible US-led strike.

Several hours later, a Syrian security official who wished to remain anonymous told AFP the country was expecting an assault "at any moment," adding the authorities were ready to retaliate.

On Friday, US President Barack Obama gave his clearest indication yet that a military intervention was imminent.

He said his administration was looking at the possibility of a "limited, narrow act", while stressing that no final decision had been taken on whether to do so.

Washington says the alleged poison gas attack killed more than 1,400 people.

Damascus denies being responsible for the incident, blaming it on rebels fighting to oust President Bashar al-Assad.

Meanwhile, the head of Iran's elite Revolutionary Guards warned on Saturday that a US strike on Syria would trigger reactions beyond the borders of Teheran's key regional ally, the ISNA news agency reported.

"The fact that the Americans believe that military intervention will be limited to within Syrian borders is an illusion; it will provoke reactions beyond that country," commander Mohammad Ali Jafari was quoted as saying.