AMMAN, Jordan - The U.S. decision to begin sending direct military aid to Syrian opposition fighters might be too late, analysts and rebels say, as recent steady gains by the regime threaten to turn the tide of the war.

Syrian President Bashar al-Assad's troops have been gaining the upper hand after launching a sweeping military offensive across the country - routing rebel forces and retaking some 30 towns and villages from the opposition.

The military push, supported by Lebanese Shiite movement Hezbollah, has changed the momentum on the battlefield, dismantling rebel strongholds and forcing opposition forces to flee, according to military experts.

"For the first time, the regime is using a strategy of employing overpowering ground forces in addition to air power to deny rebels a chance to regroup," said Mahmoud Irdaisat, director of the Amman-based Military Centre for Strategic Studies.

"Right now there is not a single village or neighbourhood where the rebels can hide," he told dpa.

Until now, the United States has been reluctant to intervene militarily in Syria, and restricted its assistance to the opposition to "non-lethal" aid.

But for the first time, the U.S. has agreed to arm the rebels after its intelligence services confirmed that the al-Assad regime has used chemical weapons in the 26-month-old conflict.

Deputy White House spokesman Ben Rhodes said Thursday the additional support for the rebels would be substantively different from what the U.S. currently sends.

Declining to give details, he said: "Suffice to say it's important to note that it is both the political and the military opposition that will be ... receiving U.S. assistance."

Al-Assad's military began its fresh onslaught in May, with the rebel Free Syrian Army (FSA) reporting an average of 300 casualties each day over the past two weeks.

"We are being outnumbered, out-equipped and out-manoeuvred at every turn," said Mohammed al-Golani, an FSA battalion commander who claims to have lost 400 fighters in battles in the eastern Damascus suburb of Ghotta.

"We were prepared to face missiles and the remnants of the Syrian army - not the entire Shiite world."

Beyond simply being outnumbered, the rebels say they are hamstrung by a shortage of funds, arms and even gasoline after more than two years of fighting.

Opposition fighters are reduced to using light firearms that are no match for the heavy artillery and air power used by al-Assad's soldiers.

With a European Union decision to lift an arms embargo on the opposition - but not to fulfil it before August, analysts warn that the rebels may not survive al-Assad's fast-paced military campaign.

"The opposition waited for months for the West and the Arab Gulf to provide them with arms and military support," Salman Sheikh, the head of the Doha Brookings Centre, told dpa.

"Now with the regime gaining rapidly and the entry of Hezbollah, no matter what the West does, it will be too little, too late," he added.

In its latest estimate, the United Nations said that at least 93,000 have been killed in the war. The real fatality figure could be much higher, as the figure does not include 38,000 unverified deaths.

Among what experts call "game changers" in the regime's recent aggression is the nature and location of the areas it has recaptured from the opposition.

The military has focused on retaking the towns of al-Kussair, Khirbet Ghazleh, Sahem al-Golan and Quneitra - all strategic border towns and gateways to the rebels' supply routes from Jordan and Lebanon.

"With these victories, the regime is effectively cutting off the rebels from the outside world," said Omar Ashour, a lecturer in Middle East politics at the University of Exeter.

The rebels are clear that should al-Assad's offensive continue, then the opposition forces may soon be facing their "final hours."

Al-Golani of the FSA warned: "If we wait any longer, the next casualty will be the Syrian revolution itself."