The broadcast showed Assad speaking to staff on the occasion of International Workers Day, or May Day, at the Umayyad Electrical Station in the Tishrin Park district. Similar still images also appeared on a page used by the Syrian presidency on the popular social network Facebook.
At least 14 people were killed in Tuesday's blast, the second in the heart of the capital in two days. Rebels seeking to topple Assad have been trying to create a supply line from Jordan, so that arms bought by Saudi Arabia and Qatar can be shipped in for assaults on the city they hope to capture.
Meanwhile, the Turkey-based Syrian National Coalition, in its first public response, rebuked the leader of Lebanon's Hezbollah militant group, a day after he said that Syrian rebels will not be able to defeat Assad's regime militarily. Sheik Hassan Nasrallah had warned that Syria's "real friends," including his Iranian-backed militant group, could intervene on the government's side if the need arises.
The coalition said it hoped Hezbollah would stay out of the Syrian war, and urged Lebanon to "control its borders and urgently stop, through all available means, the military operations attributed to Hezbollah in areas close to the Syrian border."
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Hezbollah, a powerful Shiite Muslim group, is known to be backing Syrian government forces in Shiite villages near the Lebanese border against the mostly Sunni rebels fighting to topple Assad. But Nasrallah's comments were the strongest indication yet that his group is ready to intervene more substantially on the side of Assad's embattled regime.
"You will not be able to take Damascus by force and you will not be able to topple the regime militarily. This is a long battle," Nasrallah said, addressing the Syrian opposition. "Syria has real friends in the region and in the world who will not allow Syria to fall in the hands of America or Israel or the Takfiris."
Hezbollah and Iran are close allies of Assad. Rebels have accused both of them of sending fighters to assist Syrian troops trying to crush the 2-year-old anti-Assad uprising, which the UN says has killed more than 70,000 people.