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Syrian troops backed by Lebanese Hezbollah fighters clashed Wednesday with rebel forces south of a Damascus suburb that is home to a major Shiite Muslim shrine in an attempt to secure the area surrounding the revered site, activists said.

State TV said its forces was able to clear rebels out of one neighborhood, al-Bahdaliya, outside the suburb of Sayida Zeinab, home to the ornate, gold-domed shrine of Sayida Zeinab, the Prophet Muhammad's granddaughter. Meanwhile, rebel forces claimed they took control of a hospital in a village south of the shrine neighborhood, from which they were battling regime forces and allied militias.

Opposition fighters control several suburbs of the capital, trying to threaten the heart of the city, seat of President Bashar Assad's power. But the regime has largely been able to keep them at bay.

The area surrounding the Sayida Zeinab suburb, about 10 miles south of Damascus, has seen fighting before. But the regime forces and Shiite Hezbollah fighters launched an intensified assault there on Monday, according to Rami Abdul-Rahman, the director of the Syrian Observatory for Human Rights.

The assault appears aimed at decisively pushing rebels back and securing the suburb of the shrine, said Abdul-Rahman. The Observatory is a Britain-based group of anti-regime activists that has a network of activists on the ground.

Before the war, Shiite pilgrims from outside Syria regularly visited the shrine. Last year, rebels kidnapped Iranian pilgrims visiting the area, accusing them of being spies.

Now protection of the shrine has become a rallying cry for Shiite fighters backing Assad. Lebanese guerrillas from Hezbollah as well as Iraqi Shiite militiamen have been reported fighting in the area in the past weeks, though it was not clear of Iraqis were involved in the new assault.

The Syrian uprising began more than two years ago with peaceful protests against Assad, but later grew into a civil war that the U.N. says has killed more than 93,000 people. In recent months, the conflict has taken overtly sectarian overtones, particularly with the overt participation of Hezbollah on the side of the regime, dominated by Alawites, an offshoot sect of Shiite Islam.

The rebels are largely Sunni Muslims, and have also been joined by Sunni fighters from countries in the region.

U.S. officials estimate that there are 5,000 Hezbollah militiamen fighting alongside the regime; while thousands of Sunni foreign fighters are also believed to be in Syria, including members of Jabhat al-Nusra, an Al Qarda affiliate that is believed to be among the most effective rebel factions in Syria.

Hezbollah fighters were instrumental in a recent victory for the regime forces, regaining control of a strategic town in the central Homs province after more than a year in rebel hands.

Buoyed by that victory, regime forces have been on an offensive to dislodge rebel fighters from areas they hold in Damascus, as well as the country's heartland in Homs province. That would enable Assad's regime to secure a corridor leading to the coastal enclave that is the heartland of Syria's Alawites and also home to the country's two main seaports, Latakia and Tartus.

Also on Wednesday, state TV said an explosion at a military depot outside Syria's coastal city of Latakia left six people lightly injured on Wednesday.

State TV said a "technical error" caused the explosion at a base used by the army corps of engineers. The Britain-based Observatory said it did not know the cause of the explosion in what it described as an ammunition warehouse. It said 13 people were injured, including some in critical condition.

The difference in the casualty figures could not be immediately reconciled. The Observatory said smoke was rising from the depot, on the southern edge of the city. Latakia activists on Facebook also reported the arrival of ambulances and helicopters after the explosion.

Syria's northwestern Latakia province, which borders Turkey, is a regime stronghold whose population is predominantly Alawite. The coastal capital Latakia is fully under regime control but some northern parts of the province are in rebel hands.

In villages to the north of the city, government troops on Tuesday destroyed an ammunition dump and several tunnels operated by Al Qaeda affiliate Jabhat al-Nusra, Syria's state news agency said on Wednesday. It quoted a military source as saying five Libyan fighters were killed in the operation.

The United States decided last week to send arms to the rebel forces. But the G-8 summit of world leaders ended Tuesday without mentioning arms in its final statement, reflecting a split on the issue. The group includes Russia, which opposes the idea.