The rebel Free Syrian Army (FSA) claimed responsibility for the twin explosions that rocked the military headquarters in central Damascus on Wednesday.

State television said that four guards had died in the attack, which also sparked a gun battle between troops and rebels.

However, the army said all commanders and officers inside the building, on Ummayad Square, were unhurt in the assault.

Television footage was broadcast of a white van exploding next to the headquarters, with a second blast inside that came 10 minutes later.

The FSA's Military Council in Damascus said via its Facebook page that "the Free Syrian Army has struck the military headquarters in Damascus's Umayyad Square."

Gun battle breaks out

After the blasts, gunfire erupted around the army headquarters. A journalist working for Iran's English-language Press TV service was shot dead and another wounded by sniper fire, with the Iranian outlet saying opposition fighters were behind the shooting.

The two reporters were covering the twin bombings that targeted a top military building in the heart of the city earlier on Wednesday.

"Insurgents in the Syrian capital Damascus have attacked Press TV staff and killed one of our reporters," news anchor Bardia Honardar said on air.

Blame for rebels and supporters

Press TV's news director, Hamid Reza Emadi, said the journalist, an Iranian national, was killed instantly when shot in the neck while reporting live for the station.

"We hold Turkey, Saudi Arabia and Qatar responsible for the murder of our correspondent in Damascus, (as) they provide weapons to the insurgents in Syria and the insurgents are using sniper fire... to provide an atmosphere of fear and intimidation among the local population as well as journalists," he added.

Press TV is financed by the Iranian government, a supporter of Syrian President Bashar Assad's regime.

Four foreign journalists have been killed in Syria since fighting broke out in March 2011.

jlw, rc/lw (AFP, Reuters)