This Wednesday, March. 19, 2014 photo provided by the anti-government activist group Aleppo Media Center (AMC), which has been authenticated based on its contents and other AP reporting, Syrians inspect the rubble of destroyed buildings following a Syrian government airstrike in Aleppo, Syria. (AP Photo/Aleppo Media Center AMC)

BEIRUT (AP) — Syrian troops captured a famous Crusader castle Thursday near the border with Lebanon after days of intense clashes with opposition fighters, the latest in a series of battlefield gains by government forces along the frontier, state media and officials said.

Lebanese private broadcaster Al-Mayadeen TV aired live footage of Syrian troops raising the two-starred government flag over the towering hilltop perch of the Crac des Chevaliers. The loud crackle of celebratory gunfire could be heard as troops moved around the sprawling fortress, which appeared intact.

Forces loyal to Syrian President Bashar Assad have seized at least four towns and villages in the past two weeks near the border with Lebanon as the government tries to sever rebel supply lines across the rugged, mountainous border. The sharpest blow to the rebels came with the fall of their stronghold of Yabroud near Lebanon's eastern border on Sunday.

But the government capture of the Crac des Chevaliers, which dates back to the back to the 12th century and dominates the surrounding valley and terraced hills, marked another painful setback, for symbolic reasons as much as strategic. Rebels had controlled the castle since 2012.

"Our efforts, those of the Syrian Arab Army and the National Defense Forces, were crowned today by raising the Syrian flag on the Crac des Chevaliers," an unnamed Syrian army colonel told Al-Mayadeen. "The battle had been going on for more than a month during which several nearby villages were liberated."

Syrian state television said troops "wiped out terrorists who were entrenched in the castle." Syrian authorities refer to opposition fighters as terrorists.

A Homs-based activist who goes with the name of Beibares Tellawi told The Associated Press that the castle fell into the hands of government troops earlier Thursday, a day after rebels and the government agreed that opposition fighters be given safe passage to Lebanon. He added that troops captured Hosn, where the citadel is located, after an intense bombardment by the Syrian air force.

The Britain-based Syrian Observatory for Human Rights said fighting around Hosn killed 12 fighters Thursday. The dead included the local leader of the Jund al-Sham Islamic group. Lebanese television stations identified the dead commander as Abu Suleiman Dandashi, a Lebanese national.

Syria's state news agency said "a number of terrorists were killed" as they tried to flee Hosn toward Lebanon. An activist in Homs who goes by the name of Samer al-Homsi said people fleeing Hosn were ambushed near the Lebanon border and many were feared dead.

The Crac des Chevaliers, one of the world's best-preserved castles from the era of the Crusades, had been in rebel hands since 2012. As with nearly all of Syria's heritage sites, the citadel has been damaged by the current conflict.

Amateur videos posted online have shown shelling and airstrikes hitting its thick stone walls.

Last week, the United Nations warned that ancient Christian and Muslim sites in Syria are under attack and demanded an immediate halt to the destruction of the country's cultural heritage.

U.N. Secretary-General Ban Ki-moon, UNESCO Director-General Irina Bokova and the joint U.N.-Arab League mediator on Syria, Lakhdar Brahimi, issued a joint statement citing "alarming reports" that Syrian historical sites are being deliberately targeted for ideological reasons.

Six sites in Syria have been designated as World Heritage sites by UNESCO, the U.N.'s cultural and educational agency, and the officials said some have suffered "considerable and sometimes irreversible damage." They listed the Crac des Chevaliers as one of them.

Also Thursday, a senior humanitarian official said the first convoy carrying desperately needed aid supplies via Turkey is set to cross the border into Syria.

U.N. regional Humanitarian Coordinator Nigel Fisher said that trucks loaded with food supplies, blankets, mattresses, family kits and medical supplies bound for the Syrian city of Qamishli are leaving the Turkish border crossing at Nusaybin.

Fisher said in a statement that the delivery will mark the first time in three years that the U.N. has been able to deliver aid to Syria from Turkey.

Previously, the Syrian government has refused to allow U.N. aid in through Turkey, which is a staunch supporter of the rebellion against Assad.

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