AMMAN/BEIRUT - Syrian forces unleashed new tank and rocket bombardments on opposition neighborhoods of Homs on Saturday while diplomats sought UN backing for an Arab plan to end 11 months of bloodshed in Syria.Activists said seven people were killed in the latest attacks in a week-long government siege of Homs, a battered city at the heart of the uprising to oust President Bashar Assad. "The four included a 55-year-old woman. They were killed by shelling that hit their building in Bab Amro," a Homs opposition activist, Mohammad Hassan, told Reuters by satellite telephone.The bloodshed followed a day of violence across Syria on Friday, when bombings targeting security bases killed at least 28 people in Aleppo and rebel fighters battled troops in a Damascus suburb after dark.Assad has ignored repeated international appeals, the latest from the European Union, to halt his violent crackdown."I am appalled by the reports of the brutal attacks by the Syrian armed forces in Homs. I condemn in the strongest terms these acts perpetrated by the Syrian regime against its own civilian," EU foreign policy chief Catherine Ashton said."The international community must speak with one voice, demanding an end to the bloodshed and urging Assad to step aside and allow a democratic transition."However, the world is deeply divided over how to end the Syria conflict. On Sunday Russia and China vetoed a draft UN Security Council resolution sponsored by Western and Arab states that backed an Arab League call for Assad to step down.