Free Syrian Army chief Riyadh al-Asaad on Thursday called for foreign air strikes on "strategic targets" in Syria to speed up the fall of the regime, in a telephone interview with AFP.

"We are not in favour of the entry of foreign troops as was the case in Iraq but we want the international community to give us logistical support," said FSA chief Colonel Asaad, who is based across the border in Turkey.

"We also want international protection, the establishment of a no-fly zone, a buffer zone and strikes on certain strategic targets considered as crucial by the regime," he said.

In contrast, the leader of the main Syrian opposition group in exile said after talks in Paris on Wednesday that his organisation does not want to see rebels launch armed attacks on President Bashar al-Assad's forces.

Amid fears of the deadly anti-regime protests in Syria since mid-March turning into civil war, Burhan Ghaliun of the Syrian National Council said the FSA should try to avoid direct confrontation with regime troops.

"We would like this army to carry out defensive actions to protect those who have left the (regime's) army and peaceful demonstrations, but not take on offensive actions against the army," he said.

But Asaad said limited foreign intervention would "allow us to triumph in a relatively short time" and singled out missile batteries in coastal areas as prime targets for attack.

Later on Thursday, the FSA claimed an attack on a bus in the centre of Syria that killed seven senior military pilots.

The attack, carried out by "armed Bedouins", took place near the city of Palmyra, said an opposition member based in the flashpoint region of Homs.

In a statement the FSA said "a brigade carried out the attack on a bus transporting pilots on the road between Palmyra and Homs, killing seven officers and the driver."

The FSA now has 20,000 men in its ranks, which are swelling each day, according to the colonel.

"We are determined to liberate our people and to make the regime fall," he said, charging the regime was now counting on "mercenaries" sent by Lebanon's Shiite militia Hezbollah and by Iraq's radical Shiite cleric Moqtada Sadr.

The United Nations says more than 3,500 people, most of them civilians, have been killed since the protests first broke out in mid-March, while thousands of people have been detained.

The FSA has stepped up attacks in recent weeks and openly claimed responsibility for deadly operations against the army and pro-regime militiamen.

"We hope the Assad regime will soon meet the same end as that of (Moamer) Kadhafi in Libya," said Asaad.

US State Department spokesman Mark Toner said in late September it was no surprise that the Syrian opposition was turning to violence as "an act of self-preservation" against the bloody crackdown.

The opposition had "shown extraordinary restraint in the face of the regime's brutality" and it would be "unfortunately, a natural development" for it to turn violent the longer its members are jailed and killed, he said.