Opposition leader Tzipi Livni on Saturday called for "more intense international intervention" in Syria and "more decisive Israeli condemnation" of the continuing "massacre" being perpetrated by Syrian President Bashar Assad in the country.Speaking while on a tour of Druse villages in the North, Livni said that "the crimes committed by Assad give Israel a diplomatic opportunity to create avenues of action together with the Arab League and the more moderate Arab countries against Syria - a partnership that can also help in the struggle against Iran in the future."Former UN chief Kofi Annan is currently in Syria as the joint special envoy of the UN and the Arab League, in attempts to broker a ceasefire and political dialogue between government and opposition.On Friday he urged the UN Security Council to agree on a strong and unified message in support of his efforts. Annan said that unified pressure from the Security Council on Syria has succeeded in the past, such as when it pressed Damascus to withdraw forces from neighboring Lebanon, envoys said. That withdrawal was completed in 2005.Russia and China have twice vetoed Security Council resolutions condemning the government of Assad for his year-long attempts to crush pro-democracy demonstrations. Negotiations on a third draft resolution - this time penned by the United States and calling for a ceasefire and humanitarian access for aid agencies - have stalled over disagreements about who in Syria should be the first to stop fighting and who is to blame for the conflict.Underlining Assad's growing isolation, four members of the Gulf Cooperation Council (GCC) announced Friday the closures of their embassies in protest against its violent crackdown, the Saudi Press Agency (SPA) said.Kuwait, Oman, United Arab Emirates and Qatar were to follow in the footsteps of Saudi Arabia and Bahrain and halt diplomatic activity in Syria, the GCC was quoted as saying in a statement.Russia condemned the decision, saying it was vital to keep communication open.Reuters contributed to this report.Israel has been reticent to take an active part in diplomatic action against the violent crackdown in Syria which is entering its second year and has claimed more than 8,000 lives.Livni called for a change in approach, saying "this is not the time for polite diplomacy. The time has come for the Israeli government to take an active and clear stance, as well as diplomatic action."She added: "Israel would do well to join the principled and moral group that is coming out against the Assad regime and be part of efforts to provide the Syrian people with needed humanitarian aid."