Syrian rebels move along the border with Turkey

AP

Syrian authorities on Thursday sent text messages over cell phones nationwide with a message for rebels fighting President Bashar Assad's regime: "Game over."

The messages signed by the Syrian Arab Army also urged the rebels to surrender their weapons and warned the countdown to evict foreign fighters has begun. The texts appear to be part of the regime's psychological battle against the rebels, but are highly unlikely to have any effect on fighters intent on toppling Assad, reports The Associated Press.

Syrians say they began receiving the messages a day after rebels bombed a military command centre in Damascus — a major security breach of the heavily guarded capital that highlighted the regime's growing vulnerability in the face of a rebellion growing in confidence and capabilities.

People with cellular subscriptions received the messages while those with prepaid phones did not, residents in the Syrian capital said.

Despite the high-profile attack, the two sides have been locked in a stalemate after 18 months of conflict. Activists say the death toll since the conflict began in March last year has recently topped 30,000, with nearly two-thirds of the casualties reported in the past six months.

In August, Syrian army helicopters dropped leaflets warning rebels in Damascus to hand over their arms and seek amnesty.

In Geneva on Thursday, the United Nations' refugee agency said the U.N. and its partners are launching a revised appeal for $487.9 million to help support Syrian refugees. It said 2,000 to 3,000 refugees are crossing into neighboring countries each day.

The UNHCR said 294,000 Syrian refugees are registered or awaiting registration in neighbouring countries.

Earlier Thursday, a Lebanese TV station broadcast footage showing Syrian government troops driving rebels from a building they had briefly occupied a day earlier after a double car bomb attack struck army headquarters in Damascus.

The images from Lebanon's Al Manar TV station further demonstrated the scale of the security breach of the heavily guarded capital by rebels determined to topple the Assad regime.

The fighters detonated car bombs that engulfed the army headquarters in flames, followed by three hours of gunbattles in and around the compound Wednesday.

The government said four army guards were killed and 14 people were wounded, including civilians and military personnel.

The carefully orchestrated attacks were the most dramatic security breach in the centre of the capital Damascus since July, when rebels detonated explosives inside a high-level crisis meeting in Damascus that killed four top regime officials, including Assad's brother-in-law and the defence minister.

They highlighted the regime's growing vulnerability, even as the 18-month battle to bring down Assad is locked in a stalemate.