The European Union on Thursday began work to toughen sanctions against Syria, looking at adding firms and individuals to a list of allies of Syrian President Bashar al-Assad already hit by sanctions. Several diplomatic sources said experts from the 27-nation bloc were discussing ways Thursday of \"widening sanctions\" against Damascus. \"The idea is to move up a level,\" said a diplomat who asked not to be identified. \"Talks are focusing on new names and entities.\" The EU to date has slapped two sets of sanctions against Assad\'s regime over its savage crackdown on protesters, with EU foreign ministers late May adding the president to a blacklist of 23 Syrian officials hit by an assets freeze and travel ban. Sources told AFP however that new proposals might not be ready for approval by foreign ministers meeting in Luxembourg next Monday. Further sanctions could be approved at an EU summit in a week, on June 23-24. Several European nations -- notably Britain, France, Germany and Portugal -- have joined Washington in pushing for a UN resolution condemning the crackdown but this is opposed by permanent Security Council members China and Russia. Beijing and Moscow on Thursday issued a joint statement opposing outside interference in the unrest in the Arab world. Also on Thursday, the United States condemned Syria\'s \"outrageous use of violence\" after Syrian rights groups reported nearly 1,300 civilians killed in three months of bloodshed.