DOHA: Foreign ministers of the "Friends of Syria" group meet on Saturday for crucial talks on arming the rebels trying to topple the Damascus regime, with loyalist forces making key gains on the battlefield.

On the eve of the meeting in the Qatari capital, main armed opposition group the Free Syrian Army (FSA) told AFP it had new weapons that could turn the tables on President Bashar al-Assad's regime.

"We've received quantities of new types of weapons, including some that we asked for and that we believe will change the course of the battle on the ground," FSA media spokesman Louay Muqdad said.

"We have begun distributing them on the front lines, they will be in the hands of professional officers and FSA fighters," he said, without saying where the weapons came from.

Senior opposition figure Burhan Ghalioun said the FSA had recently received "sophisticated weapons", including "an anti-aircraft defence system".

The reported boost to the rebel arsenal comes after Washington vowed to increase support for the insurgency after declaring that Assad had defied warnings not to use chemical weapons -- an accusation denied by Damascus.

But Syria's armed opposition wants more sophisticated weapons and has urged its friends in the West and Arab states to impose a no-fly zone over areas it controls.

The CIA and US special operations forces have been training Syrian rebels for months, since long before President Barack Obama announced plans to arm the opposition, the Los Angeles Times reported Friday.

Training for rebel forces covers the use of anti-tank and anti-aircraft weapons and has been carried out at bases in Jordan and Turkey since late last year, the newspaper reported, citing unnamed US officials and rebel commanders.

Officials in Washington said Friday that the US military has expanded its presence in Jordan to 1,000 troops, in a show of force amid the raging civil war in neighboring Syria.

The United States is concerned about a possible spillover of violence from Syria to its southern neighbor Jordan, a key US ally and one of only two Arab states to have signed a peace treaty with Israel.

Syrian rebel appeals for more aid follow a string of military gains by loyalist troops backed up by Lebanon's Iran-backed Hezbollah group.

They have retaken Qusayr in the central province of Homs near Lebanon and are trying to recapture rebel-held areas of the key northern city of Aleppo.

US Secretary of State John Kerry will attend the Doha talks with the foreign ministers of Britain, Egypt, France, Germany, Italy, Jordan, Qatar, Saudi Arabia, Turkey and the United Arab Emirates.

Washington has given no details about the kind of military support it could offer the rebels, and President Barack Obama is cautious about becoming embroiled in an increasingly sectarian conflict.