GENEVA - Russia and Western powers locked horns over a peace plan for Syria on Saturday as UN mediator Kofi Annan warned the conflict could spread across the Middle East and beyond.Foreign ministers and international diplomats were meeting in Geneva with governments still in dispute over whether Syrian President Bashar Assad, condemned in the West but still backed by Russia, could have any role in a political transition.Moscow objects to any solution imposed on Syria from outside. The United States and its European and Arab allies see no way ahead while power remains in Assad's hands.As the diplomats gathered at the UN complex by the shores of Lake Geneva, the Syrian army rained mortar fire on pro-opposition areas in Deir al-Zor, Homs, Idlib and the outskirts of Damascus, opposition activists said.Government troops were fighting rebels of the Free Syria Army in several places. Syria's border with Turkey was also tense following a Turkish military build-up in response to Syria's shooting down of a Turkish warplane last week.More than 10,000 people have been killed since the anti-Assad uprising broke out and the past few weeks have been among the bloodiest.UK's Hague calls for sanctionsAnnan said the crisis should never have reached this point."Either unite to secure your common interests or divide and surely fail in your own individual way. Without your unity, your common resolve and your action now ... nobody can win and everyone will lose in some way," he said.The mood of pessimism was reinforced by a senior US official who said the talks might not reach a deal on Saturday."Discussions remain challenging," the official said.British Foreign Secretary William Hague said Assad and his close associates could not lead any transition. Accountability for war crimes must be part of such a process, he added in his speech to the meeting.Hague called for the UN Security Council to start drafting a resolution next week setting out sanctions against Syria, a move that he noted put him at at odds with Russia.Chinese Foreign Minister Yang Jiechi told the talks the solution lay with the Syrian people, not outsiders, but that Beijing fully supported Annan's mediation.EU foreign policy chief Catherine Ashton said as she headed for lunch that she was hopeful a good solution would be reached.The foreign ministers of the five permanent members of the UN Security Council - Russia, the United States, China, France and Britain - were all attending the talks along with Turkey, Kuwait, Qatar, UN Secretary-General Ban Ki-moon, Arab League chief Nabil Elaraby and the EU's Ashton.Also present was Norwegian Major General Robert Mood, who headed a failed UN ceasefire monitoring mission to Syria and was witness to some of the violence.Iran, Syria's closest regional ally, and Saudi Arabia, a foe of both Damascus and Tehran and leading backer of the rebel forces opposing Assad, are not represented. Nor is anyone from the Syrian government or opposition.According to a draft document from Annan, seen by Reuters, the envoy envisages the setting up a transitional government of national unity which can establish a neutral environment for political change. It would have full executive powers."It could include members of the present government and the opposition and other groups, but would exclude from government those whose continued presence and participation would undermine the credibility of the transition and jeopardize stability and reconciliation," it said.That proposal is the stumbling block as it effectively means Assad cannot be involved, which Moscow and Beijing views as imposing a solution. The Syrian opposition also demands that he be barred from any role.United Nations chief Ban, opening the closed-door meeting, underlined the need to reach an agreement "today".At least 16 killed in fighting across countryThe Syrian conflict has evolved from peaceful protests against the Assad family's four-decade rule to something akin to a civil war with a sectarian dimension.The world has condemned the ferocity of Assad's forces' crackdown - including military assaults on pro-opposition areas and mass arrests - but has been unable to halt violence which threatens to draw in the region's religious and political rivalries and alliances.On Sunday, activists reported shelling in Homs, Idlib and the outskirts of Damascus. At least 16 people had been killed, the British-based Syrian Observatory for Human Rights said.Syrian forces reentered Douma, near Damascus, after weeks of siege and shelling. Bodies lay in the street and soldiers were carrying out searches in hospitals, activists said. Electricity and water were cut off.Abo Abdullah, 50, said he and his five children left Douma on Sunday morning fearing attacks by government forces as they swept through the town in search of dissidents."I saw at least three bodies on a street corner, some houses were destroyed, others were on fire. Only a few people remained inside the city. Those who can, leave," he said."I saw a body on the side of the street and dogs were gathering around it, it was really horrible."State news agency SANA said security forces were raiding hideouts in Douma of "armed terrorist groups" and had killed, wounded or arrested scores.Although the government routinely refers to its enemies as foreign-controlled terrorists, Assad himself conceded this week that the country was now in a state of war."The Russians have set out a series of objections with the current draft. The Russians are stonewalling quite a bit," a Western diplomat told Reuters as the talks paused for lunch."A redraft of the text is looking likely," she said, referring to Annan's draft proposal.Annan, the former UN chief and the special international envoy on Syria, is hoping for consensus on a plan for a unity government that would exclude controversial figures from leadership - effectively meaning Assad would step down."We are here to agree on guidelines and principles for a Syrian-led political transition that meets the legitimate aspirations of the Syrian people," he said in opening remarks."No one should be in any doubt as to the extreme dangers posed by the conflict - to Syrians, to the region, and to the world."His appeal gave a note of urgency to the need for world powers to move closer in their positions as the 16-month-old conflict in Syria deepens. His plan for a negotiated solution is the only one on the table.