Syrian state televison says the country's national security chief has died from wounds suffered in a rebel blast in Damascus on Wednesday

General Hisham Ikhtiyar is the fourth high-level Syrian official to die in the bombing.

Damascus has been the scene of fierce clashes this week between government troops and rebel forces. Syrian state media Friday said government troops have recovered full control of a volatile neighborhood in the capital, the Midan District

Violence raged across Syria on Thursday. The London-based Syrian Observatory for Human Rights said more than 300 people were killed in what is believed to be the deadliest day in the 16-month uprising against President Bashar al-Assad.

Meanwhile, Russia has rejected Western criticism of its veto Thursday of a U.N. Security Council resolution that would have threatened Syria with sanctions if it does not halt violence.

China also vetoed the resolution, which would have extended the U.N. monitoring mission in Syria. The mandate of the mission is due to expire Friday. Council members are expected to meet again to consider a resolution that would extend the mandate for a brief period

In another development, Syrian rebels seized control of major border posts with Iraq and Turkey Thursday, leading Iraqi officials to close off the border with Syria.