Syrian forces took control of two villages near the Lebanese border on Saturday after driving out rebels, state media said, helping Syrian President Bashar al-Assad secure the strategic road connecting Damascus with Aleppo and the Mediterranean coast.
The fall of Flita and Ras Maara, two of the last rebel bastions in the area, could push militants and refugees over the border into Lebanon – risking further destabilizing the Mediterranean country whose own 15-year civil war ended in 1990.
"The Army and Armed Forces restored stability and security to the towns of Ras Maara and Flita ... after getting rid of the fleeing terrorists and destroying their weapons," state news agency SANA said.
The Syrian government has been making incremental gains along the highway as well as around Damascus and Aleppo in recent months, regaining the upper hand in a conflict that entered its fourth year this month.
Assad needs to secure the route to transport chemical agents out of Syria via the coast, as part of an agreement with the Organization for the Prohibition of Chemical Weapons (OPCW) to remove Syria's chemicals weapons arsenal.
Meanwhile, the United Nations' humanitarian chief on Friday told the U.N. Security Council that the Assad regime's delays in withholding cross-border aid deliveries were "arbitrary and unjustified" and against international law.
Valerie Amos gave her first such report since the Security Council last month approved a resolution demanding that both the government and opposition allow immediate access everywhere in the country to deliver aid.
"The administrative arrangements that have been put in place for clearance for our convoys are quite convoluted," Amos told Reuters in an interview, after briefing the U.N. Security Council about how much-needed aid is still not reaching many in Syria.
The war in Syria, which began with largely peace protests in March 2011, has evolved into a civil war with sectarian overtones that has left more than 140,000 people dead.
It has also heightened sectarian tensions between Shia and Sunni Muslims in Lebanon, causing insecurity and political gridlock.
Violence from the conflict spilled over into Lebanon Saturday, when a suicide bomber killed himself and three soldiers at a Lebanese army checkpoint in the border town of Arsal, Lebanese security sources said.
Arsal is home to thousands of Syrian refugees but also Syrian rebels and their Lebanese allies who have fled a Syrian army advance on the Syrian side of the border. Three other soldiers were wounded, the sources said.
Lebanese Sunnis accuse the Lebanese army of conspiring with forces loyal to Assad and the Lebanese Shia armed group, Hezbollah, which has sent fighters into Syria to support Assad against Sunni rebels.
The attack hit just hours after a speech by Hezbollah leader Sayyed Hassan Nasrallah, who said he was protecting Lebanon by fighting in Syria against Sunni rebels.
"Some in Lebanon say the resistance (Hezbollah) has nothing to do with Syria," Nasrallah told supporters Saturday via a television link from an undisclosed location in Lebanon.
He added that he sent forces into a foreign war in Syria because if he didn't, Sunni rebels would eliminate everyone in Lebanon if they won in Syria, Reuters reported.
"The problem in Lebanon is not that Hezbollah went to Syria, but that we were late in doing so," Nasrallah said. "This resistance will remain solid, with its head held high, protecting its people and its nation."
Nearly 2.5 million Syrians have fled to Egypt, Iraq, Jordan, Lebanon or Turkey since the conflict erupted in 2011. By the end of 2014, Syrian refugees are expected to number more than 4.1 million.
“Syria has become the great tragedy of this century — a disgraceful humanitarian calamity with suffering and displacement unparalleled in recent history,” said Antonio Gutteres, the United Nations High Commissioner for Refugees, last September.
Of the current refugees, more than 1.3 million are under the age of 18.
Al Jazeera and wire services