The Arab League approved on Saturday a sweeping package of measures censuring Syria, clearing the way for a significant escalation of international pressure against President Bashar al-Assad and deepening the isolation of his increasingly embattled government.

The 22-member regional body said it would suspend Syria’s membership, impose sanctions and seek U.N. help unless the Syrian government stops using violence to suppress the country’s eight-month-old uprising. At least 3,500 civilians have died in the crackdown, according to the United Nations.

The Arab League also summoned opposition leaders to a meeting within the next three days to formulate “a unified view of the coming transitional period,” offering the clearest indication yet the region is moving closer to the Obama administration position that he should step down.

The unexpectedly severe measures suggested that Arab states are already starting to plan for a post-Assad era. That will in turn increase pressure on other powers that have so far refrained from taking action against Syria, notably Russia, China and Turkey, opening the door to the kind of international consensus on Syria that the United States has been seeking to build, analysts said.

“This is a diplomatic game-changer,” said Salman Shaikh, director of the Brookings Doha Center in Qatar. “It’s a significant moment that foretells greater international isolation and pressure on the Assad regime.”

In Washington, President Obama issued a statement hailing the Arab move as evidence of “the increasing diplomatic isolation of a regime that has systematically violated human rights.”

The resolution adopted at an emergency meeting in Cairo represented a rare display of Arab solidarity against a fellow regional power, marking only the third time a nation has been suspended. Egypt was ejected from 1979 to 1989 for signing a peace treaty with Israel, and Libya was suspended in March after the uprising there.

Just two countries voted against the measures, Yemen and Lebanon, with Iraq abstaining, demonstrating the extent of Syria’s isolation in the Arab world. The sanctions will be discussed at a ministerial meeting in the coming days, and the league said it would consider granting recognition to the Syrian National Council, an umbrella opposition body that has struggled to be accepted by the international community.

The suspension is to take effect Wednesday, giving Syria a small window in which to implement an Arab League peace plan that had called for the withdrawal of troops from cities and a halt to attacks on protesters. The details of the proposed sanctions will be discussed at a meeting in the coming days, the league said.

“Syria is a dear country for all of us, and it pains us to make this decision,” Qatar’s prime minister, Sheik Hamad Bin Jasim al-Thani, told reporters in Cairo. “We hope there will be a brave move from Syria to stop the violence and begin a real dialogue toward real reform.”

But after flouting the terms of the agreement for the past 10 days, launching a new offensive against the central city of Homs and killing more than 250 people nationwide, Syria seemed unlikely to suddenly pull back its forces, activists said. As protesters surged onto the streets of Syrian cities to stage demonstrations hailing the Arab League’s decision, the Local Coordination Committees, a group that monitors and supports protests, said 18 more civilians were killed.

In Damascus, angry Assad supporters throwing stones and carrying sticks and knives attacked and damaged the Saudi Arabian Embassy, according to the kingdom’s Washington mission and news agency reports.

On Sunday, tens of thousands of Syrians swarmed into central squares in the cities of Damascus and Aleppo to protest the decision, offering a reminder Assad can still count on significant support despite the uprising challenging his rule.

Syria’s government was defiant, accusing the Arab League of bowing to American interests and warning of unspecified “consequences on the whole region.”

“It’s obvious that they’re following the U.S. agenda,” said Syria’s Arab League representative, Yousef Ahmad, according to the Syrian news agency SANA.

Lifting Arab ‘cover’

The measures mark a significant setback for the Assad government, which has until now confidently boasted that regional and world powers won’t dare take meaningful action against Syria because of the potentially destabilizing impact of regime change in the strategically located and religiously mixed country.

And until now, Arab states have indeed seemed hesitant to criticize Syria. The Arab League did not meet to discuss the spiraling violence until August, five months after the protests erupted, and Saturday’s measures came only after weeks of deliberation, deadlines and unfulfilled promises by the Assad government.

The slow response contrasts with the swift measures taken to suspend Libya weeks after the February uprising, opening the door to the adoption of the U.N. resolution that authorized NATO airstrikes and helped bring about Moammar Gaddafi’s demise. The United States cited the Arab censure of Libya as being instrumental in determining its decision to support military action.

International military intervention in Syria is still considered a remote possibility despite repeated calls by protesters for NATO to enforce a no-fly zone. But the lifting of Arab “cover” will make it harder for Russia and China to justify their vetoes of tougher action, including possible sanctions, at the U.N. Security Council, said Shaikh.

Turkey, which has repeatedly condemned Assad but taken no concrete steps against him, may also be encouraged to fall in line with the rest of the region and adopt economic sanctions that could have a significant effect on its neighbor’s economy, he said.

Assad can count on the support of Iran as well as neighboring Lebanon, whose government is controlled by the militant Shiite Hezbollah movement. Fears of triggering a regionwide war in which Iran and Hezbollah spring to Syria’s defense are among the reasons why world powers have been reluctant to intervene.

The Shiite-led government in Baghdad, which abstained from voting, is concerned that regime change in Syria would destabilize Iraq’s delicate sectarian balance, and it has shown no inclination to support measures against Assad.

‘A morale booster’

Yet amid signs that the Syrian uprising is growing more militarized, with protesters acquiring arms and defected soldiers attempting to form a rebel army, analysts don’t entirely rule out international intervention.

“Right now, there’s still hesitancy, but if this takes off into some kind of full-on conflict, you’ll see Arabs and Turks and the U.S. making different decisions,” said Andrew Tabler of the Washington Institute for Near East Policy.

Many in the protest movement say that peaceful demonstrations remain the most effective way to take on the Assad regime and that tougher world action is likely to encourage the regime. But after eight months of inaction, the league’s move sends the message that violence gains international attention, said Beirut-based activist Shakeeb al-Jabri.

“It’s definitely a morale booster . . . because it shows there are alternatives to the military solution that many are waiting for,” he said. “But at the same time, suspension from the Arab League isn’t going to end the conflict, and many believe this result only came because Syria started showing signs of civil war.”

Correspondent Leila Fadel in Cairo contributed to this report.