The Arab League suspended Syria on Saturday, pledging new sanctions against the Bashar Assad regime for its bloody eight-month crackdown on protesters and urging member states to withdraw ambassadors from Damascus.

The Arab bloc’s suspension – just the third since it was founded in 1945 – underlined the Assad government’s deepening international isolation over a brutal counterinsurgency campaign estimated to have killed more than 3,500 people.

“We were criticized for taking a long time, but this was out of our concern for Syria,” Qatar’s Prime Minister Sheikh Hamad bin Jassim al-Thani told reporters at League headquarters in Cairo. “We needed to have a majority to approve those decisions.

“We are calling all Syrian opposition parties to a meeting at the Arab League headquarters to agree to a unified vision for the transitional period,” said Sheikh Hamad, who is also foreign minister of Qatar, which holds the organization’s rotating chairmanship.

Earlier this month the Arab League drafted a plan to stem the violence. That program called for Syrian forces to withdraw from major cities, as well as the release of political prisoners and official dialogue with opposition groups. Damascus accepted the proposal, but took no visible steps to implement it.

Since the plan’s announcement, more than 100 people have been killed in the protest hotbed of Homs alone, according to a Human Rights Watch report issued on Friday.

Activists said at least six people were killed nationwide on Saturday.

Walid Phares  – a Mideast affairs adviser to US Republican presidential hopeful Mitt Romney and author of the recent book The Coming Revolution: Struggle for Freedom in the Middle East – said the League decision reflects the “internationalization” of the Syria crisis.

“Expect Iranian counter-escalation to respond to this move. One concern here is that Syria, Hezbollah and Iran may trigger a regional, or a series, of clashes in multiple places to deter the Arab League leadership” from following through, Phares told The Jerusalem Post in an email.

Qatar’s Sheikh Hamad said the League may ask the United Nations to step in to help protect the rights of Syrians.

“If the violence and killing doesn’t stop, the secretary-general will call on international organizations dealing with human rights, including the United Nations,” he said.

Syria’s Arab League representative struck back that the decision was “not worth the ink it was written with.”

It was clear that “orders were issued to them from the United States and Europe to hasten a decision against Syria,” Youssef Ahmed told Syrian state television.

Saturday’s move was surprising given that the Arab League rarely condemns the actions of member states.

In 1979, the bloc suspended Egypt for 10 years after Cairo signed a peace deal with Israel, and in February of this year it suspended Libya as the death toll mounted in the popular revolt against Muammar Gaddafi. Libya’s suspension from the 22-member League paved the way for the UN Security Council to support NATO intervention in the country.

On Saturday, Syrian TV reported a demonstration outside the Qatari Embassy in Damascus, while Assad’s opponents hailed the League’s new resolve.

“This gives a lot of strength to the position of the Syrian National Council. This is now an Arab position,” said Basma Qadmani, a member of the executive committee of the Syrian National Council, the most prominent opposition group.

The League was split between states such as Saudi Arabia and others that are hostile to Syria’s ally Iran, and countries such as Yemen, struggling to quell widespread unrest, and Lebanon, where Syria’s influence looms large.

Yemen and Lebanon opposed the suspension and Iraq abstained in the vote, Hamad said. Political and economic sanctions would begin on Wednesday, he said, without elaborating on the sanctions’ exact nature.

Sources familiar with the League’s deliberations said countries like Somalia and Mauritania had taken a cue from Sudan and backed the tougher stance on Syria, while Algeria was persuaded to switch camps under pressure from France.

“Algeria took the same position, which was challenging for the Arab League to achieve because of the uprising Algeria had earlier in the year and its location close to Tunisia, Libya and Egypt,” a source at the League said.

US President Barack Obama welcomed the decision, saying the suspension had further isolated Assad.

“These significant steps expose the increasing diplomatic isolation of a regime that has systematically violated human rights and repressed peaceful protests,” Obama said in a statement from Honolulu, where he is hosting an Asia-Pacific summit.

“We will continue to work with our friends and allies to pressure the Assad regime and support the Syrian people as they pursue the dignity and transition to democracy that they deserve.”

“The United States commends the principled stand taken by the Arab League and supports full implementation of its efforts to bring a peaceful end to the crisis,” the office of Secretary of State Hillary Clinton quoted her as saying in a statement.

“The failure of the Assad regime, once again, to heed the call of regional states and the international community, underscores the fact that it has lost all credibility. As today’s Arab League decision demonstrates, the international pressure will continue to build until the brutal Assad regime heeds the calls of its own people and the world community,” Clinton said.

French Foreign Minister Alain Juppé said it was time for international bodies to take more action. “France appeals to the international community to hear the message sent by the Arab states, to take its responsibilities and to thus act without further delay,” he said in a statement.

German Foreign Minister Guido Westerwelle said the decision sent an important signal to those in the Security Council who had up to now prevented a clear resolution on Syria.

Andrew Tabler, a fellow at the Washington Institute for Near East Policy and author of the new book In the Lion’s Den: An Eyewitness Account of Washington’s Battle with Syria, advised the US Senate Foreign Relations Committee last week to take a multi-pronged approach in confronting Damascus.

Tabler identified seven key steps in applying pressure on the Assad regime: Form a contact group with regional allies and Syrian opposition leaders, help opposition leaders draft a coherent working strategy, work to persuade remaining Assad supporters to defect and push for more human-rights monitoring of the government.

Tabler also urged lawmakers to prepare for militarization of the conflict, and to explore “the possibility of the creation of ‘nofly,’ ‘no-go’ or ‘buffer zones,’” and Security Council action.

“Security Council resolutions will serve as the basis for maximizing multilateral pressure, especially comprehensive sanctions and possible future use of force,” he said.

Farid Ghadry, president of the US-based Reform Party of Syria, called in his blog on Friday for robust international engagement in helping bring down Assad.

“In politics, as in life, one either is more apt at making friends or at making foes. In the Middle East, no Arab regime has as many enemies as the Assad regime,” Ghadry wrote.

“Consider only a partial history of its actions against Syrians, Lebanese, Iraqis, Turks, Israelis, Jordanians, Palestinians and Americans, and you will get a sense of how easy it is to demolish this anomaly of terror,” he wrote. “Everyone wants this cancerous existence terminated.”

Reuters contributed to this report.