ANTAKYA, Turkey: Syrian rebels have been closely monitoring the regime's chemical weapons sites, but don't have the means to seize and secure them, their newly elected military commander told The Associated Press.

Gen. Salim Idris, who defected from the Syrian army in July, said he was ''very afraid'' a cornered Syrian President Bashar Assad would unleash such weapons on his own people.

Syria is said to have one of the world's largest chemical arsenals.

Earlier this week, Syria's UN ambassador said the regime would not use such weapons under any circumstances.

However, recent US intelligence reports indicated the regime may be readying chemical weapons and could be desperate enough to use them.

Idris, a 55-year-old German-trained electronics professor, was chosen earlier this month as chief of staff by several hundred commanders of rebel units meeting in Turkey.

With the election of Idris and a 30-member military command centre, Syria's opposition hopes to transform largely autonomous groups of fighters into a unified force.

The reorganisation came after Syria's political opposition won international recognition this month as the sole representative of the Syrian people.

In an interview late Tuesday, Idris said the rebels could defeat the regime within a month if supplied with anti-aircraft weapons.

Assad's troops are stretched thin and have lost ground in recent months, particularly in northwestern Syria, but have kept rebel fighters pinned down with massive air bombardments.

The West has refused to supply Syria's opposition with weapons for fear they could fall into the hands of Islamic militants among the rebels, such as Jabhat al-Nusra, which was designated a terrorist group by the US last week.

Idris played down possible threats posed by al-Nusra, saying that while the group was not part of the new unified command, ''they are not terrorists''.

Without foreign military help, driving out the regime could take ''one, two or three months,'' Idris said, speaking in a hotel lobby in the southern Turkish town of Antakya near the Syrian border.

He claimed that more than 120,000 armed men are fighting Assad's military, a figure difficult to confirm independently in the chaos of Syria's civil war.

Idris said the new military command represents the vast majority of these fighters, and that he has begun taking command inside Syria in recent days.

Idris said that on Tuesday, he spent much the day near the central city of Hama, observing a successful rebel attempt to capture five regime checkpoints.

Syria's conflict began with a popular uprising in March 2011, but quickly turned violent, with protesters taking up arms in response to a brutal regime crackdown. Activists say more than 40,000 Syrians have been killed and aid officials estimate some three million people have been displaced by the fighting.

Idris portrayed Assad as a powerless figurehead, saying decisions are made by his inner circle of fellow Alawites, followers of an offshoot of Shia Islam.

The ruling elite won't surrender and is willing ''to set everything on fire,'' warned Idris, who served in the military for 35 years, including as dean at the military's technical college in the city of Aleppo, now a major battleground.

The regime ''can and will'' use chemical weapons unless the international community forces Assad to leave, Idris said, speaking in fluent German.

He said rebel fighters are trying to monitor the chemical weapons sites.

''We know exactly where they are and we are watching everything,'' Idris said. ''But we don't have the capability to put them under our control.''

The West has shown little desire to intervene militarily in Syria's conflict, but President Barack Obama has said the regime's use of chemical weapons against the rebels would be a ''red line''.

US officials have said the regime launched more than a half-dozen Scud missiles in recent days, the first time it has used such weapons in this conflict.

Idris said he was aware of three launches, adding that two missiles fell in Syria's eastern desert and a third on the outskirts of a town close to Aleppo.

Idris, citing information from rebel sympathisers within the regime, said Scud missiles are being trained at northwestern Syria, the area close to the Turkish border, and could be fired at any moment.