BBC News with Jonathan Izard

Fighting in Syria appears to be moving closer to the center of the capital Damascus. In the past two days, there have been clashes between government forces and rebel fighters in much of the southern area of the city. This report by Jim Muir.

The sound of heavy machine gun exchanges echoed around the Midan district on the southern approaches to Damascus city center.

Unverified

video posted by activists on the internet showed a car completely engulfed in flames in a street in Midan, saying it had been full of security forces or pro-regime militia. Other video footage showed large numbers of security forces and armored vehicles in the adjacent district of Nahaitia – the first time such combat forces have been deployed close to the city center. Many people there have been hearing the sounds of battle for the first time since the uprising began 16 months ago. Earlier, Russia said Western efforts to get Moscow to change its policy on Syria amounted to

blackmail

.

Health regulators in America have approved the first drug shown to help reduce the risk of HIV infection. The drug, Truvada, can be used by those at high risk of infection, such as anyone who may engage in sexual activity with HIV-infected partners. The US Food and Drug Administration stressed that the drug should be used as a part of comprehensive HIV-prevention plan. Studies showed the drug reduced the risk of contracting HIV by up to 75%.