The Arab League has called on the UN Security Council to create a joint peacekeeping force for Syria and has urged Arab states to sever all diplomatic contact with President Bashar al-Assad's government.
Syria immediately rejected the moves, spelled out in a resolution adopted on Sunday by the league's foreign ministers meeting in Cairo.
Arab foreign ministers also decided to halt all diplomatic dealings with representatives of the Syrian government, though they did not demand the expulsion of Syrian ambassadors from member states.
Saudi Foreign Minister Saud Al-Faisal conveyed the 22-nation league's deep frustration with Syria, telling delegates that it was no longer appropriate to stand by and watch the bloodshed.
"Until when will we remain spectators?'' he said. The bloodshed in Syria, "is a disgrace for us as Muslims and Arabs to accept".
The new efforts came a week after Russia and China vetoed a resolution at the UN Security Council that would have supported an earlier Arab League plan for Assad to give up power and begin a transition to a new government.
But Nabil el-Arabi, the league's chairman, said he had received a message from Russian Foreign Minister Sergei Lavrov that expressed support for the league's efforts and an expanded "observer" mission. Lavrov earlier defended Russia's veto and subsequently visited with Assad in Damascus.
The league suspended an observer mission in Syria last month, and on Sunday Arabi accepted the resignation of Sudanese General Mohammed al-Dabi, who led the troubled mission. Arabi recommended appointing former Jordanian foreign minister and UN envoy to Libya Abdel Ilah al-Khatib as Dabi's replacement.
Al Jazeera's Rawya Rageh, reporting from Cairo, said the request for a peacekeeping force raised a number of questions, including whether Syria would agree and which Arab countries might contribute troops.
Syria's state news agency said the country rejected the Arab League decisions, which were taken without a Syrian representative present.
Syria's ambassador to the Arab League, Ahmed Youssef, was quoted as saying that Saudi Arabia and Qatar were "living in a state of hysteria after their last failure at the UN Security Council to call for outside interference in Syria's affairs and to impose sanctions on the Syrian people".
The United Nations has historically deployed armed peacekeepers only with the host country's consent.
Arab foreign ministers have been engaging in "intensive talks" with Russia and China and are hoping they can help encourage Assad to accept a peacekeeping force as an alternative to escalating conflict, Rageh said.
The league also agreed to step up economic sanctions and provide the Syrian opposition with political and financial support, though it again refrained from recognising the Syrian National Council - the most prominent of anti-Assad groups.
"Its a very difficult process to recognise the SNC - the Arab League made it clear to the opposition that the body as a whole cannot do it, but rather the individual countries will need to do that on their own," Rageh said.
Tunisia will host a "Friends of Syria" meeting on February 24 to attempt to build an international consensus on how to end the violence. Tunisia's foreign minister said the meeting will include Arab, regional and international states, and Qatari Prime Minister Hamad bin Jassim Al Thani, who is also the country's foreign minister, said he backed the proposal.
Homs shelling continues
Syrian forces continued their bombardment of the city of Homs, and activist groups said 67 people people were killed during violence across the country on Saturday, including 14 defectors from the Syrian military.
Opposition neighbourhoods in Homs were hit by tank and rocket bombardments in the government's continuing crackdown on protesters there, with the city's Bab Amr area coming under concentrated fire.
In-depth coverage of escalating violence across Syria
Security forces have also made house-to-house raids over the last two days in Homs, which has been under siege for the last week, anti-government activists have said.
They say at least 300 people have been killed there since the government's latest assault began on February 4.
In Hama, the Syrian Revolutionary General Commission (SRGC), a rights group that has organised protests against Assad's rule, says that the army is continuing to maintain a heavy presence.
The group said troops raided the city's al-Sharia neighbourhood and that heavy gunfire and mass arrests were reported from there and at least three other districts.
General killed outside home
Reports of violence between security forces and anti-Assad forces were also reported from Zabadani and Douma, which is just outside the capital Damascus.
The Syrian Observatory for Human Rights (SOHR), an UK-based activist group, reported that 10 soldiers were killed in an ambush by army defectors on Friday in the Idlib area, near the Turkish border.
The defectors hit a patrol between two villages with hand grenades and roadside bombs, the SOHR said.
Army defectors also fought government troops for hours overnight in the al-Qaboun neighbourhood of Damascus. State media reported that anti-government forces had also killed a senior Syrian military doctor outside his home in the capital.
The SANA news agency reported that "an armed terrorist group" had killed Brigadier-General Issa al-Khouli, described as a doctor and hospital director, in the Rukneddine district on Saturday.
The Revolution Leadership Council, an anti-Assad group in Damascus, alleged that the government had carried out the killing itself.