Fighting raged Thursday between Syrian government troops and opposition fighters near the Syrian capital Damascus, dpa quoted opposition activists as saying. An upsurge in attacks by opposition fighters on state institutions in Damascus prompted authorities to tighten security around vital facilities, they activists. The measure comes a day after three blasts targeted the Interior Ministry, killing at least nine people, activists said. "The battles are raging in the suburban areas of Daraya, Arbeen, Harasata," said Haytham al-Abdullah, a Syrian activist based in Damascus. "Jets are using TNT barrel bombs to strike the opposition fighters bases in these areas," he told dpa. US officials said Wednesday that President Bashar al-Assad's government had begun using Scud missiles and barrel bombs against opposition fighters. The Britain-based Syrian Observatory for Human Rights said a car bomb exploded Thursday near a complex housing Syrian army officers in the area of Katana on the outskirts of Damascus, causing casualties.