Syrian government troops have heavily bombarded western town of Rastan, near Homs, killing at least 15 people. Witnesses say a number of buildings in the ancient town were destroyed. Activists say, more than 50 people have been killed in Rastan since a military operation there started at the weekend. The offensive comes despite an amnesty offer by President Bashar al-Assad's government and the release of hundreds of detainees. But Syrian opposition leaders meeting in Turkey rejected the amnesty and said they will continue to push for regime change.Meanwhile, the United States and France both said the amnesty would not be enough. U.S. State Department spokesman Mark Toner said the Syrian president's effort fell short and that all political prisoners need to be freed.In Paris, French Foreign Minister Alain Juppe said Syrian authorities must be “much more ambitious, much bolder than a simple amnesty.