By Khaled Yacoub Oweis and Angus MacSwan
AMMAN/BEIRUT (Reuters) - Syrian forces unleashed new tank and rocket bombardments on opposition neighborhoods of Homs on Saturday while diplomats sought U.N. 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 al-Assad.
Mohammed Hassan, one opposition campaigner in Homs, told Reuters by satellite telephone that a 55-year-old woman was among those killed by shellfire on the Bab Amro district.
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 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.
However, the world is deeply divided over how to end the Syria conflict. On Sunday Russia and China vetoed a draft U.N. Security Council resolution sponsored by Western and Arab states that backed an Arab League call for Assad to step down.
The government offensive on opposition-held, mostly Sunni Muslim areas of Homs has killed at least 300 people in the past week, according to activists. Food and medical supplies are running low in blockaded areas, where many people are trapped in their houses, fearful of coming under fire if they step out.
Accounts could not be independently confirmed as Syria restricts access by most foreign journalists.
Youtube footage provided by activists showed a doctor at a field hospital next to the body of the woman. "Shrapnel hit her in the head and completely drained her brain matter," he says.
Big guns also pounded other Sunni neighborhoods in Homs that have been at the forefront of the uprising.
The 46-year old president belongs to the Alawite sect, an offshoot of Shi'ite Islam that has dominated the majority Sunni country since Assad's late father took control in a 1970 coup.
Security forces have also made house-to-house raids in Homs in the last two days. The bodies of three people shot by snipers were pulled from the streets on Saturday, activists said.
YouTube footage from Friday showed two tanks said to be on the edge of Bab Amro, one firing its main gun across a highway.
"The indiscriminate shelling is killing mostly civilians," Fawaz Tello, an Egyptian-based member of the opposition Syrian National Council, told Reuters.
"Assad cannot push his troops into street fighting...so he is content with shelling Homs to bits until civilian losses pressure the Free Syrian Army to withdraw and regime troops can enter these neighborhoods without taking any serious losses."
Elsewhere in Syria, the Syrian Observatory for Human Rights said 10 soldiers were killed in an ambush by army defectors on Friday in the rebellious Idlib region on the border with Turkey.
The defectors hit a patrol between two villages with hand grenades and roadside bombs, the British-based Observatory said.
In Damascus, Free Syrian Army rebels fought for four hours on Friday night against troops backed by armored vehicles who had entered al-Qaboun neighborhood, activists said.
The fighting between government and rebel soldiers showed how opposition to Assad has increasingly evolved from pro-democracy street protests to armed insurrection.
World powers fear a slide into all-out civil war which could inflame a region already riven by revolts and rivalries from Bahrain and Yemen to Iran and the Israeli-Palestinian conflict.
Gulf Arab states, the United States, Europe and Turkey are leading diplomatic efforts to force Assad to end his 11-year rule. But they have ruled out a military intervention of the kind that helped bring down Libya's Muammar Gaddafi last year.
Assad can count on the support of Russia, Syria's main arms supplier and an ally stretching back to the Soviet era, as well as Iran. Moscow, which is keen to counter U.S. influence in the Middle East, insists foreign powers should not interfere.
Kamel Ayham, a Eurasia Group analyst, said Syria was also the nexus of a regional power struggle, with Assad's fate the focus of competition between Sunni and Shi'ite Muslim countries.
At the United Nations, Saudi Arabia circulated a draft resolution backing an Arab peace plan for Syria among members of the General Assembly on Friday, diplomats said. The text echoed the one vetoed by Russia and China in the Security Council.
Like the failed draft, the assembly text "fully supports" the Arab League plan floated last month. The assembly is due to discuss Syria on Monday and vote on the draft later in the week.
Russia and China blocked the Security Council draft, saying it was unbalanced and failed to blame Syria's opposition, along with the government, for violence in which thousands have died.
The United Nations, which says it can no longer tally casualties, estimated in mid-December that the security forces had killed more than 5,000. A week later, the government said armed "terrorists" had killed over 2,000 soldiers and police.
Eurasia's Ayham said the Russian and Chinese vetoes indicated that change was not imminent. As the rebel forces lacked structure and a unified command, Assad would keep the military edge, but would find it hard to stamp out the revolt.
"In the next few months, Syria will transition from civil conflict into civil war. Assad's power and control over the country will diminish and civilian casualties on both sides are expected to rise," Ayham said.
(Additional reporting by Patrick Worsnip at the United Nations and Dominic Evans in Beirut; Editing by Alistair Lyon)