CAIRO (Reuters) - Arab states are appealing to world powers to help end the crisis in Syria after months of failed efforts to persuade President Bashar al-Assad to halt a 10-month crackdown on his opponents.
The cornerstone of their efforts - a 165-strong peace monitoring effort - was thrown into doubt on Tuesday when Gulf Arab states began withdrawing 55 of their monitors, saying they had failed to stem the violence.
The deputy head of the 22-member Arab League said the remaining monitors would continue their work.
However, Arab League chief Nabil Elaraby and Qatari Prime Minister Hamad bin Jassim al-Thani, who heads the organization's committee on Syria, wrote to U.N. Secretary General Ban Ki-moon requesting a meeting to seek the Security Council's support for the League's faltering peace effort.
One ambassador to the League said that bringing in the United Nations Security Council could lead to a tougher set of measures if Assad fails to comply.
"The Syrian regime did not implement the Arab plan under existing Arab pressure, so there was no other way except to approach the Security Council," the ambassador at the League said before the announcement of the letter and on condition of anonymity.
The League's new plan agreed at the weekend calls on Assad to step down, transfer power to his deputy and allow the formation of a unity government.
If the plan is adopted, he said, the Security Council would determine measures to push Syria to comply, such as economic sanctions similar to those imposed by Arab states, an arms embargo or restrictions on movements by Syrian diplomats.
The next steps are unclear, with both the Arab League and the Security Council split on how much pressure to exert on Assad and how.
Security Council member Russia is one of Assad's few remaining allies and is still selling arms to Syria. In October it joined fellow permanent member China in vetoing a Western-crafted resolution that threatened an arms embargo.
The head of the monitors, Sudanese General Mohammed al-Dabi, left Cairo to return to Damascus on Tuesday after telling the League the level of violence had fallen since they arrived in Syria in late December, an assertion hotly contested by Assad's opponents.
The decision to enlist U.N. support came after a weekend meeting of Arab foreign ministers that revealed differences, with Qatar and Saudi Arabia, regional rivals of Syria's ally Iran, pressing for the monitors to be recalled and tougher measures implemented. Iraq, Lebanon and others resisted.
Iraq is seen as wary of antagonizing its neighbor Iran and an ally of Syria, while Lebanon's politics have long been overshadowed by its larger neighbor Syria. However, only Lebanon failed to back the League's latest plan.
The League agreed sanctions on Damascus back in November when Syria's presence in the body was suspended, but they were not implemented by all Arab states and some oppose them still.
"We reject sanctions because they have a negative effect on the people and not the regime," Iraqi government spokesman Ali al-Dabbagh said after a meeting at the League's Cairo headquarters. He added that Iraq still supported the Arab League's efforts to end the Syrian crisis.
The ambassador to the League said the Arab sanctions had not been fully effective because states around Syria - Iraq, Jordan and Lebanon - did not implement them.
He said the line being followed by the League on Syria was similar to the Gulf Arab stance towards Yemen, where Gulf states called upon President Ali Abdullah Saleh to step down.
In contrast, the League took a more drastic approach with Libya's leader Muammar Gaddafi when it referred Libya to the Security Council, providing an opening to foreign intervention.
Gaddafi was killed after NATO air power weakened his attempts to end an insurrection.
"The Arab League is trying to work a Yemeni-style model as opposed to any Libyan model, which means it is more focused on this kind of political transition with a handover of power rather than foreign intervention," said Salman Shaikh of the Brookings Doha Center.
Additional reporting by Yasmine Saleh; Writing by Tom Pfeiffer; editing by David Stamp