The nine nations that expelled Syrian envoys plan to push for tougher sanctions, Britain said as the U.N. Security Council was to meet on the Syrian crisis. The European Union was separately considering \"a further tightening of sanctions on Syria,\" British Foreign Secretary William Hague said. In addition, Syrian teams signed up for the 2012 Summer Olympic Games, to take place in London in July and August, could be banned from the Games, Hague said Tuesday, confirming an earlier report. Syrian Olympic Committee Chairman Mowaffak Jomahas said in response to the earlier report Britain had no right to ban Syrian athletes. Hague said Tuesday it would \"be up to us who comes into the United Kingdom.\" The United States, Britain, Canada, Australia, France, Germany, Italy, Spain and Bulgaria said Tuesday in a coordinated action they were expelling Syria\'s ambassadors, charges d\'affaires and other diplomats over Friday night\'s massacre of 108 civilians, including 49 children under age 10 and 34 women. Switzerland, Belgium and the Netherlands joined, declaring the Syrian envoys to their countries \"personas non grata.\" Greece summoned Syria\'s envoy to express its \"disgust and strong condemnation\" of the slaughter. Syria had no immediate comment on the actions. Governments often respond in kind to diplomatic maneuvers such as expulsions and censures. While fresh U.N. sanctions will be pursued by the West, military intervention in Syria is not being considered, Hague said. \"There is no support, no unanimity, about any intervention in the U.N. Security Council,\" he said in remarks cited by the Los Angeles Times. \"All our efforts are going to support the Annan plan and to try to bring about a peaceful transition.\" The Annan plan is an all-but-ignored six-point peace plan put together by U.N.-Arab League special envoy for Syria Kofi Annan and endorsed by the Security Council last month. The opposition Local Coordination Committees said 72 people were killed Tuesday. Annan met with Syrian President Bashar Assad Tuesday, cautioning him time was running out to honor the peace plan and warning him the crisis had reached \"a tipping point\" following the villager killings in the Houla agriculture area of western Syria northwest of Homs. \"The international community will soon be reviewing the situation,\" he said he told Assad. The Houla massacre was one of the worst single incidents of the 14-month old uprising. The U.N. human-rights office, after initially blaming Syrian government artillery for most of the deaths, said Tuesday it now believed pro-government militias were responsible for all but 20 of the deaths. Most of the dead appeared to have been shot at close range in \"summary executions of civilians, women, and children,\" the office said. Annan, speaking to reporters, urged \"the armed opposition to cease acts of violence,\" but he said he made clear to Assad he held the regime -- \"as the stronger partner in this conflict\" -- primarily responsible for the peace plan\'s failure to halt the bloodshed. Syrian Deputy Foreign Minister Faisal Mekdad rejected Annan\'s assertion the regime bore primary responsibility for the failure. Syria has not committed \"a single violation of Annan\'s plan or the initial understanding between Syria and the United Nations,\" while the opposition had not committed \"to a single point,\" he told reporters Tuesday. Annan deputy Jean-Marie Guehenno, a former French diplomat, was to brief the Security Council Wednesday. Permanent council member China, which has blocked any Security Council move to censure the Syrian regime, is to preside over the Security Council for a month starting Friday.